BULLETIN No.
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REPUBLIC ÖF KENYA
MINISTRY OF NATURAL RESOURCES
GEOLOGICAL SURVEY OF KENYA
IROSPECTING
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(Metallurgist) '
(Revised by F. W. Ä. Timms, A.R.S.M., B.Sc, Assistant
Commissioner (Mines) and J. Walsh, B.Sc.; Ph.D., Chief
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Geologist)
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Five Shillings W 1971
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Scanned from original by ISRIC - World Soil Information, as ICSU
World Data Centre for Soils. The purpose is to make a safe
depository for endangered documents and to make the accrued
information available for consultation, following Fair Use
Guidelines. Every effort is taken to respect Copyright of the
materials within the archives where the identification of the
Copyright holder is clear and, where feasible, to contact the
originators. For questions please contact [email protected]
indicating the item reference number concerned.
GEOLOGICAL SURVEY OF KENYA
ISRIC LIBRARY
&£.
PROSPECTING FOR
MINERALS
(Second Revision)
by
A. L. STEWART, A.C.S.M., A.M.I.M.M.
(Metallurgist)
(Revised by F. W. A. Timms, A.R.S.M., B.Sc, Assistant
Commissioner (Mines) and J. Walsh, B.Sc., Ph.D., Chief
Geologist)
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Wageningen, The Netherlands
SIMPLIFIED GEOLOGICAL MAP OF KENYA
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CONTENTS
PAGE
I—The Law
II—Recognition of Rocks and Minerals
III—Structures of Ore-bodies
IV—Equipment
V—Methods of Search
VI—Establishment of Title
VII—Intensive Prospecting
VIII—Sampling
IX—Government Assistance
X—Simple Ore Dressing
XI—Guide to Prospecting in Kenya
1
2
5
7
9
11
16
20
22
23
26
APPENDICES
1—Reading List
2—Glossary of Terms
3—Identification Table for Minerals
30
31
34
ILLUSTRATIONS
Frontispiece—Simplified Geological Map of Kenya
Fig. 1—A lode ore-body viewed in perspective
Fig. 2—Section of a folded vein
Fig. 3—Section of a faulted vein
Fig. 4—Section of a complex vein
Fig. 5—Outcrop of a lode dipping upstream in hilly country
Fig. 6—Testing alluvials and learning
Fig. 7—A Protection Notice
Fig. 8—Plan of claims and Registration Notice
Fig. 9—Location beacon and notice
Fig. 10—Tracing the extension of an ore-body
Fig. 11—Outcrop of vein dipping southwards in undulating country
Fig. 12—Patterns of outcrops of uniformly dipping veins
Fig. 13—Prospecting windlass
Fig. 14—Coning and quartering
Fig. 15—A hand screen
Fig. 16—A hand jig
Fig. 17—A rocker
Fig. 18—A dry blower
Fig. 19—Sectional view of winnow
6
6
6
6
6
10
12
14
15
17
18
18
19
22
23
24
24
25
26
Prospecting for Minerals
I—THE LAW
1. Prospecting and mining for minerals in Kenya are controlled by the Mining Act
and its Subsidiary Legislation (Chapter 306 The Laws of Kenya) within the framework of the Constitution. A knowledge and understanding of these laws are essential
and obligatory before a Prospecting Right can be issued to an individual, either on
his own account or as agent for another individual, a company, syndicate or
partnership.
2. Under section 23 of the Constitution of Kenya (Amendment) Act 1964, all
unextracted minerals situated in any part of Kenya are vested in the Government of
the Republic of Kenya with effect from 12th December 1964, subject only to such
mineral rights as were granted before 12th December 1964 and which were still valid
on that day.
3. Under section 23 (b) of the Constitution of Kenya (Amendment) Act 1964, the
President or any persons authorized by him may, subject to any law, grant mineral
rights to any person on or after 12th December 1964.
4. Under section 9 of the Mining Act the Minister for Natural Resources (i.e. the
person authorized by the President) may appoint a Commissioner of Mines and Geology
and such other officers as are necessary for administering the Mining Act.
5. It will be clear from (2) above that ownership of land does not include ownership
of any minerals which that land may contain. The Mining Act therefore includes
legislation for the efficient prospecting, development and mining of mineral resources
and adequate protection of the surface rights of owners—or lawful occupiers—of land.
6. Section 7 of the Mining Act lists the various classes of land which are excluded
from prospecting and mining except with the consent of the person or authority in
whom the surface rights are vested. Of these Trust Land and private land are the two
categories most frequently encountered.
Any person wishing to prospect or mine must first obtain a Prospecting Right from
The Mines and Geological Department, P.O. Box 30009, Nairobi (Sections 13/14 of the
Mining Act) and then, if he wishes to prospect on Trust Land, must obtain the consent
in writing of the appropriate county council. Provision is made in section 7 (3) of the
Mining Act for appropriate action by the Minister, acting on behalf of the Central
Government, should any consent be unreasonably withheld.
7. Section 26 of the Mining Act provides for the safeguarding of surface rights of
owners or lawful occupiers of any land by requiring such owners or lawful occupiers
to be paid fair and reasonable compensation for disturbance, nuisance or damage
caused by prospecting or mining operations by the holder of the prospecting or mining
right under which such disturbance, nuisance or damage were caused.
To guard against non-payment of such reasonable compensation, non-payment of
wages or failure to secure or make safe any excavations made in the course of prospecting or mining the Commissioner may require the holder of a Prospecting Right to
deposit such sum as he may consider necessary with the Provincial Commissioner of
the province in which the holder of the Prospecting Right wishes to prospect and/or
mine (section 13 (7) of the Mining Act). At present (1971) this is normally Sh. 1,000
but may be increased according to the scale of the prospector's or miner's operations.
8. The above notes (paras. 2-7) refer to "minerals" as defined in section 2 of the
Mining Act. "Common Mineral Substances" are defined in section 2 of the Mining
Act and in Legal Notice 32 of 22nd January, 1966 and, where they occur on Trust
Land, are vested in the appropriate county council. They are not subject to the
Mining Act except in so far as their safe working is controlled by Part V of that Act
and by the Mining (Safety) Regulations.
9. Among the more important privileges granted to the holder of a Prospecting
Right—these are listed in detail in section 14—are those enabling him to create
protection areas, peg locations, and apply for exclusive prospecting licences, special
licences and special leases. These are dealt with in Parts II and III of the Act and also
in the Mining Regulations. Observance of the latter is most important to the prospector
if he wishes to be secure in his title. More will be said of this in Chapter VI.
10. Part Y of the Act deals with the powers of inspecting officers and the reporting
of certain accidents. Prospectors should take careful note of section 73, as failure to
report an accident to both the Mines and Geological Department and the District
Officer may lead to serious penalties.
11. Three sets of regulations enacted under the Mining Act are in force. These are: —
1. The Mining Regulations.
2. The Mining (Safety) Regulations.
3. Mining (Royalty on Carbon Dioxide) Regulations.
The first of these deals with general control of mining titles and the second with the
safe operation of prospecting and mining. The Act grants powers to make regulations
on numerous matters connected with prospecting and mining and, in accordance with
these powers, other regulations may be enacted from time to time, particularly in
respect of royalties. At present (1971) carbon dioxide is the only non-precious mineral
on which royalties are payable, but royalty on diamonds is also prescribed (Government
Notice 448/1951).
Other Acts of particular concern to the prospector are: —
1. Outlying Districts Act (Cap. 104).
2. Mineral Oil Act (Cap. 307).
3. Oil Production Act (Cap. 308).
4. Trading in Unwrought Precious Metals Act (Cap. 309).
5. Diamond Industry Protection Act (Cap. 310).
6. Explosives Act (Cap. 115).
II—RECOGNITION OF ROCKS AND MINERALS
1. Properties of Minerals
It is essential for the prospector to be able to recognize the minerals that he is liable
to meet in the field. The ability to do this can be gained only by handling specimens.
It cannot be acquired from books or even by looking at museum specimens inside
glass cases. It is intended in this chapter to make some suggestions that may help
the reader to obtain a working knowledge of rocks and minerals. It should be read in
conjunction with Appendix 3 (at end of book) which lists all the minerals known to
occur or likely to be found in Kenya.
Minerals have many properties that help in their identification and these are dealt
with at some length in books on mineralogy. Some properties that can be tested by
a prospector in the field with limited equipment are discussed below.
APPEARANCE
The general form of a mineral is often of as much importance as its colour, which
sometimes varies considerably in different specimens of the same mineral, whereas
cleavage or crystal form tend to greater uniformity. It is essential that the prospector
examines as many specimens as possible in order to acquaint himself with their
2
appearance. There are two ways of doing this. The first is to study an existing collection such as that at the Mines and Geological Department in Nairobi, the second is
to make one's own collection and have the specimens identified by a geologist.
HARDNESS
This is a most useful property and it is simple to make the test The hardnesses of
the ten minerals listed below are known as Mohs' Scale and are taken as comparative
standards: —
MOHS' SCALE OF HARDNESS
1
2
3
4
5
Talc
Gypsum
Calcite
Fluorspar
Apatite
6
7
8
9
10
Orthoclase
Quartz
Topaz
Corundum
Diamond
As examples of the use of the test, if an unknown mineral is scratched by quartz
and scratches orthoclase the hardness is taken as 6i, or if it does not scratch quartz or
only feebly and is also scratched by topaz then the hardness is 7.
The prospector should collect his own set of hardness minerals, but tests with finger
nail (2i), copper coin (3|), glass (51-6) and a good pen-knife (6) are useful. Minerals
of hardness 1 have a greasy feel.
STREAK
This is the colour of the mineral when finely powdered and is much more consistent
than the colour of the uncrushed mineral. The streak unay be observed either by rubbing the mineral on a piece of unglazed pottery or by finely grinding some of the
specimen, the colour being best seen when the powder is placed on white paper. It
may often be observed when the mineral is scratched during the hardness test.
SPECIFIC G R A V I T Y
This is the weight of a given volume of the mineral in relation to the weight of the
same volume of water. Exact methods of determining this property are described in
books on physics and mineralogy but the prospector can note whether a specimen is
"heavy" or "light" in comparison with known specimens of about the same size.
The process of panning utilizes this property by washing off the "light" minerals
and leaving behind the "heavies" in the pan. It is important that the prospector
should learn the art of panning, which is best taught by demonstration. Most
experienced prospectors or officers of the Mines and Geological Department will be
glad to show how it should be done.
MAGNETISM
All dark, heavy minerals should be tested for magnetism. This can be done by feeling
the specimen with a horse-shoe magnet, observing whether a compass needle reacts on the
mineral being moved close to it, or some of the mineral may be crushed and any
movement observed when a magnet is passed over the powder. Magnetite and
pyrrhotite are the only minerals affected by a horse-shoe magnet, when in situ.
2. Common Rock-forming Minerals
The minerals of this group, in various combinations, form most of the rocks that
are commonly met, and most frequently are of no value in providing workable
minerals, though some may be useful guides as to where to look for valuable mineral
concentrations. By recognizing the minerals in the field the prospector will often be
able to eliminate valueless material. The most important rock-forming minerals are : —
Quartz.—A light-coloured glassy mineral that is a constituent of silica-rich igneous
rocks, and is abundant in sands and sandstones. It has economic associations with
gold and other metals but, apart from its use in constructional materials, is only of value
by itself if exceptionally pure.
3
Felspars.—A group of light-coloured minerals which are very similar in character.
They are very common but are of economic importance only in certain special cases
where they occur in large masses.
Micas.—A group of flaky minerals, they vary considerably in appearance. The
commonest is black mica or biotite. It is of no economic importance, but sometimes
it is associated with a mica-like mineral called vermiculite which is often yellower.
White mica or muscovite is of commercial value in some cases, particularly if it is
in large pieces. Phlogopite and weathered biotite are sometimes mistaken for gold,
owing to their yellow colour.
Hornblende and augite.—They are black or dark green in colour and heavier than
the preceding minerals. They should be submitted to a laboratory for examination
if the prospector has any doubt as to their identity, particularly if found in large
quantities. It is important to be cautious v.hcs dark minerals arc discovered as caany
of the economic minerals are dark in colour and heavy.
Iron-ore Minerals.—These can most often be observed in rocks as small black
specks of magnetic material. They are of importance only when they occur as large
concentrations of high-grade ore and even then their economic exploitation depends
on low transport costs or the availability of cheap power and suitable cheap fluxes.
Olivine.—A dark green or brown glassy mineral which is rich in iron and magnesium. It is an important constituent of ultrabasic rocks.
3. Rocks
A rock is a naturally occurring aggregate of mineral particles but is not necessarily
hard, clay and sand both being rocks. Rocks may be divided into three main classes:
(1) Igneous
(2) Sedimentary
(3) Metamorphic
(1) Igneous Rocks
These are the products of cooling of molten rock. On a journey through the Rift
Valley or Central Province many examples of volcanic rocks will be seen. These have
poured out over the country in the form of lava and can be clearly seen around such
volcanoes as Longonot and Kenya. As the molten lava flowed along, it cooled until
it became solid. Lavas may have the appearance of glass such as the black obsidian
found near Kariandusi, or they may be stony such as the phonolite and trachyte found
around Nairobi. Except for some examples that contain scattered large crystals they
do not usually have any easily visible crystal structure as they have cooled too quickly
for the crystals to grow large. Where a rock has cooled at depth rather than at surface, however, the process is much slower and minerals are able to grow sufficiently
to be easily seen and identified in the hand-specimen. These coarse-grained rocks are
usually referred to as plutonic rocks. It will be seen that igneous rocks can be classified
according to their grain size which is largely resultant on the rate of cooling. They can
also be classified according to their mineral composition. For example, coarse-grained
igneous rock composed of quartz, mica and felspar associated in certain proportions
is called "granite", which is a silica-rich (or "acid") rock having little iron and magnesium in its chemical composition. A coarse-grained igneous rock consisting of felspar,
augite (or augite and hornblende) and iron ores, is called "gabbro" and as such rocks
contain little silica but much iron and magnesium they are referred to as "basic". If
the proportion of felspar is much reduced, augite or olivine become predominant and
the rocks are referred to as ultrabasic; examples are pyroxenite and dunite.
It should be noted that there is no hard and fast division between rock types and
forms intermediate both in composition and grain size are often found.
4
(2) Sedimentary rocks
When rocks are broken down by erosion the particles are carried away by such
agents as winds and rivers to be deposited elsewhere, as in lakes and seas. Such
particles eventually become cemented together so as to form new rocks which are
referred to as sedimentary rocks. The following are some of the types' found:
Sandstone is formed by the cementing together of quartz (sand) particles. If the
particles are coarse the rock is known as a grit. Rocks formed by the cementing
together of pebbles are known as conglomerates.
Limestone is often formed by the aggregation of shells or coral particles. It is
also formed by the chemical precipitation of calcium carbonate.
Shales are the result of consolidation of fine silt or mud.
As a result of movements of the earth's crust such sedimentary rocks may be lifted
up above sea or lake level and become the rocks we see in the country around us.
For example, the limestones at Chonyi and Jibana at the coast were formed in the sea
and subsequently became land- Similarly many rocks found in north-east Kenya,
between Wajir and Mandera, were laid down in the sea and were eventually raised to
form land.
As rocks decompose new rocks may appear at the surface overlying them. These
new rocks are known as superficial rocks and are a special category of sedimentary
rocks. Over iron-rich rocks latérite (murram) may be formed and over lime-rich rocks
calcrete (kunkar) is formed.
(3) Metamorphic Rocks
During earth movements rocks may be subjected to great heat and pressure so that
new minerals crystallize and new structures are formed, the resulting rocks being
known as metamorphic. Sometimes the change is so great that it is impossible to tell
what the original rock was, but the changes follow an ordered pattern.
Shales change to slates and with.more heat and pressure new minerals such as mica
are formed, their crystals or plates being arranged in planes, giving rocks known as
schists which have a finely foliated structure—i.e., the foliation is like the leaves of a
book and the rock is easily split.
Limestones recrystallize to form marbles. Quartz-rich sandstones may be metamorphosed to yield quartzites and coarse-grained rooks such as grits or granites form
gneisses which are coarsely foliated rocks which split much less readily than schists.
ni-^STRUCTURES OF ORE-BODIES
When a prospector finds a mineral which is confirmed as having economic importance and which he thinks is present in sufficient quantities to be workable he should
endeavour to determine the size and shape of the mass or body in which it occurs, so
that its extent and quantity can be assessed.
A fairly simple form that ore-bodies take is that of a lode (or "reef" as it is popularly
called) as illustrated in Fig. 1. It will be seen that the lode consists of a tabular body
inclined to the horizontal plane, which is usually the case. Certain terms used in
describing ore-bodies are included in Figure 1; they are an essential part of a prospector's knowledge and should be learnt and understood.
5
Vertical plane,
cutting lode
perpendicular
to
strike
Fig. 2 . Cross section of a folded vein
r i g . i . A iode o r e body viewed in perspective
-COUNTRY
ROCK
Fig. 4 . Cross section of a complex vein
Fig. 3 . Cross section of a faulted vein
Fig. 5 . O u t c r o p of a lode dipping upstream in hilly country
6
An ore-body may be disturbed by earth movements either by folding as shown in
Figure 2 or by faulting as shown in Figure 3 or; again, the shape of the ore-body
may be complex and irregular as shown in Figure 4.
Although the prospector will meet with these distortions and variations in shape it
is usually a good rule to assume that a body has a regular tabular shape and accept
variation only when there is definite evidence. Figure 5 is a block diagram of a regular
lode in hilly country. It should be noted that the outcrop twists and turns in and out
of the valleys and continually changes its apparent inclination, although the dip and
strike are constant.
IV—EQUIPMENT
To have success in his work—apart from a good slice of luck—a prospector must
get about the country, observe the rocks carefully and know what he is observing.
He must be properly equipped for his safari. It is assumed that the prospector can
look after himself in the African bush; if he is unable to do so then he would be well
advised to spend a while in the bush with an experienced safari man.
The specialized prospecting equipment required will now be dealt with .in some
detail.
Hammers are a most important part or the prospector's equipment and he should
have several. One should be a geological hammer with a pick head; this little tool
will receive much hard use and it is well worthwhile purchasing one of good quality.
Ths prospector should also have one or two larger hammers of 2 or 3 kg. weight for
breaking large rocks.
Chisels.—A few cold chisels are useful for cutting channel samples and if they are
to receive much use it is advisable to have a small portable forge, which is also useful
for sharpening picks.
Digging and cutting tools should 'be of good quality and well sharpened. .They
should consist of picks, shovels, jembes, pangas and crowbars. Short-handled tools are
most useful for pitting. Wheelbarrows, karais, buckets, ropes and pulleys should also
be available.
Sample sheet and bags.—The former should be a tarpaulin or metal sheet, not less
than 1.5 m. x 1.5 m., for sample splitting (see Chapter VIII). The bags should be fairly
large—20 cm. x 40 cm. would be suitable—and should be strong enough to stand up
to rough handling when full of sharp stones. They should also have a good piece of
cord or cords near the neck for fastening. Bags of heavy plastic material are cheap
and readily obtainable.
Pans.—These are a matter of personal preference, the standard sizes being approximately 20 cm. and 30 cm. diameter. They are usually made of steel, but some people
prefer copper pans which have the advantage of being non-magnetic.
Pestles and mortars vary in size and material according to the job in hand. If many
samples are to be crushed the mortar should be 12 cm. in diameter by 40 cm. deep.
Some prospectors use the cut-off bottom of a gas cylinder. A small steel mortar about
15 cm. x 15 cm. is useful for breaking specimens or small samples and an agate mortar
is useful if a mineral needs finely powdering.
Sieves are useful for checking the size to which a sample has been crushed. They
are usually referred to as having a certain mesh, which indicates the number of holes
per linear inch. Thus a 30 mesh screen has 30 holes per linear inch. In standard
specifications such as the British Standard Screen Series the thickness of the wire and
other factors are also specified.
Mineral testing outfit.—This should consist of at least the following: —
Magnifying glass
Streak plate
Pen-knife
Magnet
Hardness set
Acid bottle.
7
Apparatus for special tests include such items as a blow-pipe outfit, heavy liquids
and a geiger counter.
Surveying equipment will depend, on the prospector's ability as a surveyor but the
minimum requirements are a prismatic compass and a chain or tape. A range-finder,
a plane-table and a clinometer may also be useful.
Pegging materials.—The prospector should
following : —
Metal plates, 30 cm. x 30 cm.
Metal plates, 10 cm. x 10 cm.
Nails.
Paint and brushes suitable for lettering.
Flags.
carry
a
suitable supply of
the
If the area to be prospected is treeless some 1.5 rn. posts (for ciaim pegs) and another
at least 4 m. long (for protection notices) should be carried, or arrangements made
for them to be brought into the area as required.
Maps.—The prospector will find that good maps are a great help in his work. The
Survey of Kenya publish a most useful map of the whole of Kenya on two sides of a
sheet, showing the topography and roads. It can be purchased for Sh. 7/50 and is
referred to as "Route Map of Kenya, SK57A, 1:IM." For more detailed work there
is a 1:100,000 map series Y633, which covers the northern part of Rift Valley, Eastern
and North Eastern provinces, and most of the remainder of Kenya is covered by the
1:50,000 map series Y731, which also cost Sh. 7/50 per sheet. Geological maps of
most parts of Kenya can be obtained from the Mines and Geological Department. If
the prospector wishes to have more detailed information than is supplied by these
maps he should endeavour to obtain air photos, but the interpretation of these is a
somewhat specialized job requiring considerable training and technical equipment.
Stationery.—Perhaps the most important item of equipment is a notebook. It should
be large enough to allow the drawing of small sketch maps, and small enough to fit
in a bush-jacket pocket, say about 10 cm. x 15 cm. It should have a stiff cover and be
ruled to suit one's convenience. Small squares are fairly common, as the squares are
useful for making drawings approximately to scale. A "Lefax" loose leaf notebook is
extremely suitable.
The prospector will probably build up a small library of textbooks, geological reports
and maps, which should preferably be available to him in the field. In addition it will
be necessary to carry Government forms for permits and returns; a list of these is
given below: —
Form
No. •<
1 Application for Prospecting Right or renewal thereof (regulation 2 (1))
2 Prospecting Right or renewal (regulation 2(3))
3 Protection Notice (regulation 3(a))
4 Statement of work and application for extension of the rights conferred by
a Protection Notice {regulation 5(2))
6 Application for Exclusive Prospecting Licence (regulation 8)
8 Registration Notice; Lode Location (regulation 14(3))
10 Registration Notice; Alluvial Location (regulation 14(3))
14 Six-monthly statement of development (regulation 27(3) and regulation
37(1) (c) (i))
15 Application for renewal of a location (regulation 27(1)).
8
V—METHODS OF SEARCH
Locality
This is a mater of personal choice. In prospecting, some country may offer better
chances than others but also valuable minerals may be found in what at first sight
appears unpromising country. In choosing an area there are various factors to be
considered and transport is one of the more important—the greater the transport
charge on a mineral the more valuable it must be to become payable. Water and
labour should also be taken into consideration. Attention should be given to the
geological factors dealt with in Chapter XI as many areas of Kenya are not likely to
be productive of certain minerals. Having chosen an area there are various methods
of prospecting which may be followed viz: —
1. Random examination of outcrops or the following of float
2.
3.
4.
5.
6.
Grid traversing
Testing of alluvials and loaming
Geophysical methods
Geochemical methods
Botanical methods
Random examination of outcrops
In this method the prospector examines all outcrops he sees as he moves about the
country, sampling and recording any interesting occurrences he finds. The method is
often employed by people, such as hunters and farmers, who move from place to place.
It is common practice in East Africa for prospectors to employ herdsmen and nomads
who bring in any minerals they pick up in their wanderings and are suitably rewarded
in the event of a valuable find. It should be noted that where an ore-body is mpre
resistant to weathering than the country rock it will protrude, whereas softer orebodies cause depressions so that it is advisable to examine hill-tops and stream
courses.
Grid traversing
The systematic traversing of the country is the basis of all good prospecting. In its
simplest form the prospector takes a map of the country and marks off parallel lines.
He then walks along these lines on the ground and examines all outcrops and artificial
exposures of rocks, sampling any that are promising. He also investigates animal
burrows for pieces of rock thrown out in otherwise unexposed country. Details of all
samples are carefully recorded in the notebook and on the map.
It is frequently impossible to follow a rigid system of straight lines, but the prospector will usually be able to arrange his traverse lines to avoid difficult country and
thick bush and yet keep them approximately equally spaced. In laying out traverse
lines consideration should be given to the geology and mineralization of the country
and it is usually best to set them at right-angles to the strike of the country rocks and
space them as close together as the time available will permit.
Testing of alluvials and loaming
If a traverse is along a river the prospector should pan samples of alluvium taken
from points at which heavier minerals are liable to collect, such as the inner sides of
bends, heads of shoals and above boulders and rock-bars (see Figure 6). The heavy
fraction in the pan should be carefully examined for the following minerals: —
Gold, Platinum, Cassiterite, Columbite,
Monazite, Diamonds.
9
Rutile, Ilmenite, Zircon,
Kyanite,
Trench
*v.
©
.
• Panning showing values
o
o Panning not showing values
®.
'•}••' Concentration of heavier
minerais
Trench
Area
loemed
PLAN
Pits
SOIL AND SUBSOIL
SECT ION
ON LINE
A-B
Fig.6. Sketch map of the results of ( 1 ) testing alluvials and ( 2 ) loaming
10
If any of these minerals are found, panning should be continued upstream until the
mineral is no longer found. The river bed should be carefully examined for indications
of the parent lode from which the alluvial mineral came. If it is not found in the
stream the soil from the banks should be panned and it is probable that one side will
show traces of the mineral. The prospector should then continue to pan soil samples
from higher up the valley slopes until traces of the mineral again disappear. He should
then sink a pit slightly higher up and the soil should be panned and the mineral
followed uphill to its limit as shown in Figure 6.
It should be-noted that alluvial deposits in rivers may be workable, but encouraging
or- even workable alluvials are not necessarily an indication of workable lode deposits
higher up, as it is possible for the alluvials to be concentrations of the heavy, resistant
minerals from a large number of small lodes which are in themselves not workable
economically.
Geophysical Methods
Most of the geophysical methods of prospecting are complicated and need expensive equipment but there are two methods that may be within the prospector's means
and ability. They are: —
(1) Radioactive prospecting (2) Electro-magnetic prospecting.
The radioactive method requires a geiger counter or scintillation counter which is
carried by the prospector while he traverses the ground {or the instrument may be
mounted in a motor-car or aircraft). Meter readings are recorded and any particularly
high reading is investigated. It should be noted that the presence of radioactive minerals
may lead to the finding of non-radioactive mineralization, for deposits of oolumbium
(niobium) minerals are often associated with radioactivity.
Geochemical Methods
Geochemical prospecting consists of the sampling of soils and other superficial
deposits and testing of the material by chemical methods to determine the content of
metals or semi-metals, which are usually so small as to make up only a few parts per
million parts of the sample. Where the metal content is found to be several times
higher than normal it may point to the existence of an ore-body buried under the
superficial cover. This method of prospecting is generally outside the scope of the
small-scale miner.
Botanical Methods
In some parts of the world ore-bodies are indicated by the presence of certain plants.
For example, in the Zambia Copperbelt the presence of "copper-flowers" (Becium
homblei) in forest clearings indicates underlying copper-bearing bodies. This method
of prospecting has not yet been used in Kenya, but it is generally accepted that the
presence of Acacia brevispica, a straggling thorny growth, indicates quartzite or a
quartzitic horizon and it has also been found along the strike of silicified fault-zones.
Commiphora pilosissima is especially abundant over calcareous rocks, where there is a
relative decrease of grass cover. Prospectors should note the distribution of plants, as
they may thus be able to discover an association of plants and rocks.
VI—ESTABLISHMENT OF TITLE
Titles which may be granted under the Mining Act are as follows: —
1. PROTECTION AREA
This is a temporary exclusive right to prospect which may be secured on any land
open to prospecting by the holder of a valid Prospecting Right. It must be marked
on the ground by a Protection Notice—details of which are given in Regulations 4-7
and 23—which confers exclusive rights to prospect within a radius of 500 metres of
the notice for a period of 30 days. This period may be extended under certain
conditions for further periods of 30 days on payment of the statutory fees. It should
be noted that not more than one Protection Area may be.secured by the holder of a
valid Prospecting Right at any one time in the same administrative district.
11
PROTECTION
NOTICE
Oat e and time
DATE AND TIME OF POSTING :
| 5 . 30.'URS
20 3 6 2 . '
PROSPECTING RIGHT NO. 3 5 2
SIGNED:
I punched
with
I nail.
DATED 5/11 / 6 1 .
^ w r » « - Ä ( W l * ^
AGENT FOR : MZURI MINES LTD.
WITNESS:
OtN-^a.i'Va.C
0k<2-d\
Fig. 7. A Protection Notice
A typical Protection Notice is illustrated in Figure 7. It should be noted that it is
obligatory to mark the date and time of posting by pricking through the notice with
a nail or spike so that it cannot be altered subsequently.
A Protection Notice need not be registered when first posted but it is advisable
to inform the Mines and Geological Department of its approximate position. Whenever application for extension of such a notice is made details of its position must be
given.
It should be noted that it is not permissible to win minerals under a Protection
Notice since it is only a prospecting title. Should prospecting within the Protection
Area disclose any exploitable minerals it is necessary to peg and register the appropriate
class of claim(s) before proceeding to production.
2.
EXCLUSIVE PROSPECTING LICENCE (E.P.L.)
If the prospector wishes for protection while he investigates a larger area than is
available under a Protection Notice he may apply for an Exclusive Prospecting Licence.
Before applying, the prospector should go over the ground with the best map available
and pick out physical features to act as corner points for the boundaries and if possible
for the boundaries themselves of the desired area, which should be kept as small as
possible. Preferably the boundaries should be obvious to other prospectors, and roads,
rivers and straight Unes between prominent hills are the most suitable. The prospector
should also work out a programme indicating how he will prospect the area, making
sure he has sufficient capital and technical ability to do so. The application is then
submitted to the Commissioner of Mines and Geology on Form 6 of the Mining
Regulations, together with the fees. If it is accepted the area is closed to prospecting
12
and mining to everyone, including the person who has made the application, by a
Notice in the Kenya Gazette and 30 days are allowed for objections to be made. If
none is upheld the licence is prepared. The preparation of the licence may require
consultation between the Commissioner and other Government Departments or interested authorities and several weeks may pass before the licence can be issued.
E.P.Ls. carry with them obligations not only to prospect the area thoroughly and
systematically but also to submit detailed reports on the work, and the srrall prospector may be well advised to work under a Protection Notice or on claims rather
than under an E.P.L., which also has the disadvantage that it does not allow the
mining of minerals, except alluvial minerals under section 20(1) (b) (i) of the Mining
Act when permission has first been given by the Commissioner of Mines and Geology.
3. AUTHORITY TO PROSPECT ON LAND EXCLUDED FROM PROSPECTING AND MINING
Under section 16 of the Mining Act the Commissioner may grant authority to prospect on land excluded from prospecting under section 7(1) (ƒ) in accordance with such
terms and conditions as he may impose. Such authorities are usually only granted for
short periods so that the prospector can look around to see if more extensive
prospecting is worth while, in which case he would have to apply for a normal
prospecting title such as an E.P.L. or Special Licence as the creation of protection
areas or the pegging of locations in such areas is precluded.
4. SPECIAL LICENCES
As the name implies these are of a special nature and the prospector would be well
advised to obtain the services of a good lawyer and a mining engineer before applying.
Such licences may be granted only in respect of land which has been closed to prospecting and mining by the Commissioner and which is re-opened specifically for the
purpose of the licence(s).
5. LOCATION
This is the most common form of title and the prospector should read carefully the
appropriate sections of the Act and Regulations so that he has a thorough understanding of the law in relation to pegging, registering, operating and renewing the
claims comprising the location. It is by this form of title that he is best able to protect
any find so that he may either work it or sell it. The law is straightforward on this
matter, but unless the prospector makes a point of understanding it and carrying out
his obligations he may lose his title and with it the right to mine the minerals which
he has found.
The following routine is suggested for pegging claims over an ore-body: —
1. If the ore-body is not within an E.P.L. post a P.N.
2. Determine the surface extent of the ore-body and make a rough sketch-map.
On this sketch-map draw in the boundaries of the proposed claims and at the
same time decide where to post the Registration Notices (one for each location
of ten claims or less). The maximum size of the various types of claims is
governed by Regulation 15 as explained in the table below.
Claim Type
Maximum Statutory
Claim Area
Precious metals and precious stones, lode . .
Non-precious minerals, lode
Precious metals, precious stones and nonprecious minerals, alluvial
20,000 sq. m.
50,000 sq. m.
1,000 sq. m.
13
Suggested
Dimensions
200m. x 100m.
250m. x 200m.
(i) 50m. x 20m.
(ii) To suit ground
but with minimum width 20m.
3. Prepare sufficient posts and plates. The posts should be at least 1.25 metres long
to allow them to be firmly fixed in the ground and, if they are of wood, must
be at least ten centimetres in diameter. The plates should be of stout sheet metal
(old debes are often used although they need flattening for the larger plates).
They should be at least 10 cm. x 10 cm. for the claim corners and at least
30 cm. x 30 cm. for the registration notice(s). It is advisable to paint the necessary markings on the plates in camp rather than in the field. When marking
the Registration Notice plate(s) spaces should be left for the times, dates, etc.
4. The prospector will now be ready to start pegging. With the sketch-map already
prepared as guide he should insert his pegs and affix the plates, carefully chaining the distances between pegs and measuring the bearings and back bearing
along the boundaries (it may be necessary to clear the bush to do this). When
all pegs are in he must record the time and date on the Registration Notice
(pricking through in accordance with Regulation 23) and sign the notice. He
must also draw a reasonable sketch of the location with bearings and distances
between the pegs so that anyone reading the Registration Notice will be able
to locate the other pegs.
5. The prospector will then need to complete the two copies of the Registration
Notice and the three plans required by Regulation 19, and send them to the
Warden of Mines, Mines and Geological Department, P.O. Box 30009, Nairobi
together with the fees, for registration. The plans must be sufficiently detailed
so that the Warden of Mines can find the position of the claims on published
maps from the information given. Figure 8 gives a suitable form of plan.
REGISTRATION
NOTICE
PROSPECTING RIOHT No. 5O0 ISSUED AT THE OFFICE OF
THE COMMISSIONER OF MINES * GEOLOGY A T N A I R O B I
ON 1 6 - 4 - 6 4
BLOCK OF 4 H O N - P R E C I O U S M I N E R A L LODE
AS S H O W N B E L O W A N D ON P L A N LODGED
W A R D E N OF M I N E S N A I R O B I
NAME
. LOCATION
OF
DATE &
LOCATION :
TIME
OF
SIGNATURE:
A
}.
1
1
1
!-«
OF
PEGGING '.-
4>CL*tt£lcr
LOCA1IOM OF FOUR N0M-PREGIOU5 MINERALS LODE CLAIMS
R.N.
t
FAIDA
COMPLETION
15 - 5 - 6 4 - — 16 0 0 HKS.
(See,int«t)'
REGISTRATION
NOTICE
| loa ny
V s~-".
CLAIMS
WITH
TOO
m
zoo
''
E
2
1
-30cm
N.B.
10 c
Tl.
MINIMUM '
THE A R E A OF E A C H C L A I M W I L L VARY ACCORDING
CLASS OF C L A I M ( S E E REGULATION I S )
*•
Fig. 8. Plan of claims and Registration Notice
6. As soon as possible after the Warden has replied to say that he has registered
the locations the outer pegs should be replaced by stone beacons in accordance
with Part I of the Fourth Schedule to the Regulations (see Figure 9). A period
14
TO
THE
Enlargement
of Notice
Board
at
Beacon
B'
B
10
"BAHATI"
PRECIOUS
LOCATION
METALS
LODE
No. 6 2 3 / 1 - 1 0
DATE OF ORIGINAL
REGISTERED
PEGGING: '• 5 - B "fe1
AT '- COMMISSIONER OF MINES
& GEOLOGY
MAIROBl
MAZUR1. MINES LTD.
RENEWED :
ib " 5 -6 Z
50cm
MINIMUM-
Fig. 9. Location beacon and notice
of four months subsequent to registration is allowed by the mining regulations
to do this. It should be borne in mind that a location not beaconed as required
by Regulation 22(1) of the mining regulations is illegal and subject to forfeiture. It is advisable to use angle-iron set in concrete for the beacons and
to pile good cairns of stones at their bases. Trenches must be dug to indicate
the direction of adjacent pegs. As these trenches may tend to become filled by
weathering it is necessary to make them larger than laid down in the regulations and the spoil should be thrown well clear.
7. If the prospector wishes to operate a location for longer than a year it will have
to be renewed yearly. There is usually no difficulty about renewal provided that
the holder has complied with the provisions of the Act, which include the maintenance of beacons, the payment of fees, the performance of a certain amount
of development and the submission of appropriate returns. The amount of
development required can be calculated with reference to Regulation 25 and
the Second Schedule to the Regulations. The following examples may be of
assistance.
CALCULATION OF DEVELOPMENT WORK ON LOCATIONS
Example 1.—Calculate the development footage in three trenches of the following
dimensions: —
30 m. x 2 m. x 1 m., 20 m. x 2 m. x 1 m., 50 m. x 3 m. x 1 m.
Is this sufficient for one claim?
15
Trenches are calculated at 14 eu. m. to the development metre, so obtain the volume
of the trenches in eu. m., viz: —
30 x 2 x 1 = 60
20 x 2 x 1 = 40
50 x 3 x 1 = 150
250 eu. m.
250
And 250 eu. m. counts as
= 17.9 development metres.
14
Four development metres are required for one claim, so that this is sufficient for one
year on the claim.
It should be noted that trenches of depth less than one metre are not permitted
tr» be coiinted as development work.
Example 2.—A shaft 2 m. x 3 m. is sunk to a depth of 40 m. from the surface. At
a depth of 33 m. a 2 m. x 2 m. heading is driven for 6 m. What is the total
development footage and what is the excess footage on the development requirements of a location of five claims?
On referring to the tables in para. 3 (a) of the Second Schedule to the Regulations
it will be seen that this underground development counts as follows: —
Development
40
r 0-20 m. 20 m. at 2 =
30
Shaft Area 6 sq. m. -i 20-30 m. 10 m. at 3 =
L 30-40 m. 10 m. at 4 =
40
Drive Area 4 sq. m., depth 33 m. — 6 m. at 2 == 12
122
TOTAL DEVELOPMENT
Five claims required 5 x 4 = 20 development metres. Therefore 122 development
metres are in excess of statutory requirements, the total development being
sufficient for 30 lode claims.
Leases
Leases are rarely granted and then only in special circumstances. The prospecting and
mining rights granted by a lease are essentially similar to those obtained under location
title.
Vn—INTENSIVE PROSPECTING
OPENING UP THE PROSPECT
Chapter
it is next
as money
ently rich
V dealt with the search for a mineral deposit. When one has been found
necessary to determine its extent and value. This stage is most important
should not be invested in plant before there is enough ore proved, sufficito bring in enough profit to repay the investment and a reasonable interest
This matter of "proved ore reserves" is often irksome to some prospectors who,
having found a deposit, feel that they have done enough and that the investor's
demands for numerous excavations are excessive. If one considers the investor's viewpoint however, it will be realized that he must protect his investment and that he
cannot afford to risk his capital unduly. Many deposits and mineral occurrences that
look promising on surface change in value or cut out at depth, and even an ore-body
proved at surface may have inadequate underground extension or values to merit large
capital investment
16
TRACING THE OUTCROP
Sometimes the outcrop of a deposit can be traced by eye, but more often it is obscured
by soil or rubble and it is necessary to sink pits or trenches to expose it. In order to
reduce the amount of excavation the prospector should have some idea of the direction
in which the outcrop may continue. The following is a simple example of a method that
may be of assistance.
o
I
100
i
zoo
i
300
i
100 Metres
i
Fig. 10. Tracing the extension of an ore body
In Figure 10 an outcrop has been found at A; the direction of strike is N 80' E
(080°) and the dip 1:5 (approx. 11°) to the south. On the contour map lines are
drawn down-dip 125 m. apart, parallel to the strike, i.e. they represent strike at successively lower 25-metre intervals. The point at which the 275 m. contour and 275 m.
strike-line coincide will be a point where the ore-body and the land surface have thé
same elevation, i.e. if the dip has remained constant the ore-body will be found at B.
This point is then located on the ground and a trench is dug to bedrock at rightangles to the direction which the outcrop is expected to take (AB). This trench might
disclose the ore-body about ten metres north-west of the expected position, at Bi
instead of B, because of an increase in dip (the dip and strike frequently vary from
place to place). The 275 m. strike-line is then redrawn, parallel to the original line
to pass through Bt and by measurement it is found that the dip between the A and
Bi strike-lines is 1:4. Fresh strike-lines are drawn at this interval and the process is
repeated, trenches being sunk across the positions where the strike-lines coincide with
the contours. Each time the ore-body is located the strike-lines are corrected for
variations in dip and strike.
17
N
-400-S
--'
0 0
Contours
—Strike
lines
Fig. 1 1. Outcrop of vein dipping southwards in undulating country. The
vein wilt be found underground in the shaded areas only. It has
been removed from the remaining pert of the area by erosion
(b)
Fig. 12. Patterns of outcrops of uniformly dipping veins
(a) Outcrops in hilly country. W h e n the veins
are vertical the outcrop is straight and
follows the direction of strike. W i t h
dipping veins the outcrop is broader than
the true width
(b) O u t c r o p of folded vein
(c) Vein cut by two faults. The arrows indicate
the direction of movement
18
Figures 11 and 12 show some of the patterns that outcrops of uniforrily dipping
plane ore-bodies may make under varying topographical conditions. As the structure
becomes more complicated the simplest method is to trench along the outcrop rather
than to try to predict a position a few hundred metres ahead.
The foregoing applies chiefly to the outcrops of narrow and moderately dipping
ore-bodies. Wide ore-bodies or those whose dip is close to the inclination of the ground,
cover large areas and their extent should be determined by sinking pits at regular
intervals on a rectangular grid. The plan of the outcrop of a vertical ore-body is
unaffected by topography so that, provided there are no faults or folds, the outcrop
follows one bearing which is the same as the direction of strike (see Figure 12 (a)).
Where an ore-body traverses a hillside there is often a large area below the outcrop covered by boulders broken from it. It should also be noted that as the soil and
sub-soil on a hillside tend to work their way downwards any particles of float broken
from a lode also creep down the hill and may not appear at surface until they are
some distance below the projection of the reef ore-body (see Figure 6). This may lead
the prospector to believe that the whole hill is made of ore. This error can be avoided
if pits are sunk through the rubble or "fallover" to bedrock.
EXCAVATIONS
Pitting and trenching must often be employed to expose an ore-body. It is essential
that such excavations are sunk through the soil and sub-soil to the bedrock, and sometimes it may be necessary to sink through decomposed rock until unweathered bedrock is reached.
PITTING
In strong ground, pits can be sunk without any supporting timbering but the diameter
should be kept as small as possible and the pits must always be vertical. Debris from
pits should be stacked well clear of the pits and all objects that might fall and injure
the diggers should be kept away from the lip of the holes. If a pit is deeper than 2 m.
the diggers should be supplied with hard hats and there must be a ladder or other
means of egress available in the pit in accordance with the safety regulations. If the
ground being pitted is weak and liable to fall in it is necessary to hold up the sides
with timber. When timbering is necessary the prospector should obtain the advice of
an experienced miner before sinking more than a few metres.
When pits are more than 3 m. deep it becomes difficult for the digger to throw
the debris clear of the collar and it is necessary to remove it in a bucket or kibble.
This can be hauled up by a windlass which must be fitted with a ratchet and pawl
or other form of stopper. A simple windlass is illustrated in Figure 13. A windlass
Fiq. 13. Prospecting windlass
19
can be set up over the collar of a hole or alternatively a tripod carrying a pulley can
be set over the collar with the windlass a metre or two away. Only ropes made of
steel wire may be used for winding or hauling.
TRENCHING
Much of what was said regarding safety in pits should be observed in trenches.
Excavation should be kept as narrow as is practical, and if the ground is weak the lip
of the trench must be sloped back. Where trenches are too deep for throwing the
spoil out it is sometimes convenient to make ramps at the ends so that wheelbarrows
can be used. For open ended trenches along the slope on hillsides the bottoms should
be inclined to drain towards the open end.
AUGERING
In soils, highly weathered rock and soft ground such as alluvium or old mine tailings, it may be possible to obtain samples by sinking holes with an auger such as a
posthole auger, the spoil providing samples.
DEEPER EXCAVATIONS
Pitting and trenching will indicate the real extent of a deposit but the third dimension, i.e. the depth, may still be in doubt and to obtain this it is necessary to make
deeper excavations which may be difficult and, if not properly constructed, dangerous.
They should not be attempted without the supervision of an experienced miner.
Vin—SAMPLING
The object of sampling is to obtain in as small a bulk as possible material that
is representative of a much larger quantity. The ability to sample correctly is most
important to the prospector and he should have a clear understanding of the difference
between a sample and a specimen. A specimen is usually a piece of mineral or rock
taken to identify qualitatively a particular species, but a sample consists of a sufficiently
large number of particles to represent the parent body quantitatively. In other words a
specimen tells "what" a mineral or ore is, whereas a sample can be used to find out
"how much" of a valuable mineral there is in the ore.
SAMPLING PROCEDURE
The more care and time taken over sampling the better will the samples represent
the parent body, but the importance of a sample must be balanced against the cost in
time and labour used in taking it and the reason for taking it. Many prospectors in
Kenya have not taken sufficient pains over sampling and consequently little reliance
could be placed on assays made on their samples, and it has often been necessary for
them to return to the deposits for better samples, which sometimes entailed travelling
several hundred kilometres. Details of the procedure must depend on the circumstances,
but the following general rules should be observed: —
1. A clean fresh face should always be used for sampling. Outcrops tend to be
weathered, leaving a concentration of more resistant minerals at the surface; also
the sides of pits tend to get covered with a film of wash from higher up the pits.
2. Veins should be sampled by grooves across the entire width and spaced at regular
intervals along the strike. If a deposit appears to be fairly uniform then it is
permissible to take a series of chips rather than grooves but care should be taken
that the chips are obtained on a uniform pattern.
3. Care should be taken to obtain hard and soft materials in the proportion in which
they occur in the vein.
4. All samples should be clearly marked and a note made of their position at the
time of sampling, together with any relevant information about dip, strike, width,
etc.
5. Bands and veinlets that can be mined separately or nodules that can be easily
separated by hand should be sampled separately.
20
6. A sampler must avoid contamination of samples by foreign matter. Cleanliness of
equipment and methods is essential.
7. The sampler should keep in mind the reliance that may later need to be placed
on his samples.
8. If the ore is soft, a prospecting pick is a suitable tool for cutting the sample, but
in hard rock a hammer and chisel should be used.
9. The sample may be collected on a clean canvas sheet or seamless bag, but it should
be placed finally in a stout bag with strong ties and be clearly labelled.
10. A larger sample than is needed should be taken when possible and reduced by
crushing, coning and quartering to the required amount.
CONING AND QUARTERING
In order to obtain a representative sample the sampler will often have to cut much
more material than is required for assaying or than it is reasonable to transport. The
reduction of the bulk of the sample must be done in such a way that the fraction taken
is representative of the original sample. This will probably necessitate crushing, as it is
important that the particle size is such that the removal of the largest particle does not
materially affect the value of the sample. There is a relationship between the size of the
sample and the size of the largest particle that is desirable to obtain the best reduced
sample, which is also affected by the uniformity of the ore. The following table gives a
rough guide for prospecting samples:—
Size of largest piece
in millimetres
75
25
12
6
1
Minimum weight of sample
in kilograms
500
50
10
2.5
0.5
N.B.—This table applies only to preliminary prospecting samples; for the sampling
of batches of ore for shipment or purchase it is necessary to grind the ore more
finely and the sampling should be done by a professional sampler.
Samples can be reduced by coning and quartering in the following manner: —
1. Place the crushed samples on a canvas, plastic or metal sheet and mix thoroughly
by means of a shovel;
2. Build the sample into a cone by throwing it in shovelfuls onto a vertical stick
(Figure 14 (1));
3. Flatten the cone by pulling the sample outwards radially from the stick (Figure
14 (2));
4. Divide into four equal parts as shown in Figure 14 (3). It is important to have
the quarters meeting exactly in the centre so that the fine material, which is often
the richest, is equally divided amongst the four quarters;
5. Discard two opposite quarters and retain the remainder.
If correctly carried out this procedure will have divided the sample into two halves
each of which will be similar to the other and representative of the original. If necessary,
the sample should be crushed again and the procedure repeated until the sample is
reduced to a suitable bulk.
If the sample is to be sent away it is usually advisable to retain one half of the last
splitting for future reference.
21
(1) ßuiid cone around stick
throwing each shovelful
on t o t h e s t i c k
( 2 ) F l a t t e n cone
(3) Divide i n t o four quarters by
c u t t i n g w i t h plank or metal s t r i p .
Cuts should cross in exact
p o s i t i o n of s t i c k
(4) Discard opposite q u a r t e r s ^ B "
r e c r u s h material in "A" and
repeat coning and q u a r t e r i n g
u n t i l bulk and size s u f f i c i e n t l y
small
Fig. 14. Coning and quartering
IX—GOVERNMENT ASSISTANCE
It is a function of the Mines and Geological Department of Kenya to encourage the
development of the country's mineral resources. The Inspectors of Mines are experienced
mining engineers and prospectors will find that they are able to help them in many
respects. In addition to these officers, who spend much of their time in the field, the
Headquarters of the department in Nairobi are well equipped to assist the prospector.
The Warden of Mines is stationed there and is able to advise on matters regarding
titles and returns. There is a well stocked museum. The library and map-store contain
all the known information on Kenya geology. Geologists are always available to identify
specimens and advise on any further work.
The services of the assay laboratory are available to the public at moderate charges
although before submitting samples to the Chemist and Assayer it is preferable to have
them examined by a geologist who will advise whether they are worth the trouble and
expense of assays. Mineral dressing laboratories are available for the investigation of
problems of separation of saleable products from ores.
22
X—SIMPLE ORE-DRESSING
The prospector or small worker is not advised to set up ore-dressing machinery without the advice of a qualified mineral dresser. Such advice can be obtained from the
Mines and Geological Department in Nairobi, manufacturers of mineral dressing
equipment or private consultants. A short description of the simpler processes, which
require little capital outlay and may be used for preparing small bulk samples, forms
the remainder of this chapter.
HAND COBBING
This process consists of breaking large lumps of ore and picking out rich portions
and discarding pieces of gangue (waste). It is often the only process necessary in the
treatment of pegmatites. It is not usually economical to hand pick ore of less than
five centimetres in size and it is easier to sort ore which has been washed and sized.
SCREENING
As stated above, sorting is often facilitated by sizing. This is best done on a screen,
which for hand use consists of wire mesh in a frame either circular up to 45 centimetres in diameter or about 45 centimetres square. Such a sieve can be held in the
hand and the ore shaken on it to remove the fines, or the process can be carried out in
water. Larger sieves, say 60 centimetres by 100 centimetres, can be mounted on four
posts and swung on cranks, so that they can be shaken by hand or actuated by a cam
driven by a small engine. If it is desired to wash at the same time, a spray can be
mounted above the screen (see Figure 15).
BACK
VIEW
SIDE
VIEW
Fig. 15. A hand screen
HAND JIGGING
This process separates particles having different specific gravities and can "be used for
particles down to about one millimetre in size. Two procedures adopted are as
follows : —
1. The ore is placed in a hand sieve and immersed in a tub of water, then given a
jigging motion by jerking the hands downwards quickly, which tends to lift all
the particles in relation to the screen, and then the hands are raised slowly
allowing the particles to settle according to their specific gravity. By repeating
this motion the heavy particles settle on to the screen and the light ones work
their way to the surface of the mineral bed, whence they can be scraped,
after which more ore can be added. After some time the bed will become full
of heavy mineral, which should then be removed.
23
2. The above method is only suitable for treating small batches of ore as the arms
become extremely tired after jigging about 50 kilograms of rock. If it is desired
to treat larger quantities of ore the sieve should be mounted to form a hand
jig as shown in Figure 16. The bed is motivated by working the handle to
provide motion similar to that described in the first method.
T
-v-ftr-r-
n
^
<N>
-W'
^
2Û^
E I'
*''
Light—
«J :;
to
<N
_ Heavies
r
.Ore bo*
„
0% S o o o
;
4L
~
O Of) Q £
n-i
\& m K m *
-35cm
"~~~
Screen
- \
WATER
—
=i Bung
Fig. 16. A hand jig
ROCKERS AND SLUICES
Jigs are suitable for recovering coarse material, but if it is required to treat fines
(less than Imillimetre) then a rocker or sluice may be suitable. The former is shown
in Figure 17. The ore is fed on to the screen and washed with water on to the corduroy
flX
Handle
/\
n
E
Ore and water
\N
lûmm Punched plate
\
U
[ Feed
,
hopper^l
Riïfles
/
BACK
VIEW
LOK1GITUDIMAL
Fig. 1 7. A rocker
24
SECTION
and then over the riffles. Heavy minerals are caught on the corduroy and behind the
riffles. The product is passed through the rocker again or panned until it reaches a
suitable grade.
DRY BLOWING
The use of sluices and rockers requires a good supply of water, but in many areas
of Kenya water is scarce and it is necessary to use dry methods of treatment. Figure
18 illustrates a dry blower. "A" is a shaking screen, "B" a metal chute delivering
Fig. 18. A dry blower
onto "C", which is a porous tray with riffles mounted on hessian backed with wire
mesh. "D" is the wind box and "E" the bellows with clack valves opening into "D"
and with a trap below to facilitate the removal of dust. "P* is the crank which
operates the bellows and the screen. Ore is fed on to the screen and coarse material is
discarded, the fines pass on to "C" and the heavy minerals are caught behind the
riffles and the fine tailing discarded.
WINNOWS
Winnows extend the use of the principle employed in separating grain from chaff
by pouring the threshed grain from one container to another in a breeze, the chaff
being thrown away and discarded. While a dry blower may be suitable for the recovery
of heavy minerals in arid areas the winnow illustrated in Figure 19 is more suitable
for the recovery of lighter flaky minerals such as graphite or vermiculite.
25
-^-Dust
to;
o
(0
3
Coarse
flakes
Fine
flakes
Fig. 19. Sectional view of winnow
TREATMENT OF GOLD ORES
Many small workers treat gold ores without much technical assistance and if the
prospector decides to do this he should refer to "Gold Extraction for the Small
Worker" published toy Imperial Chemical Industries Ltd., and obtainable from Twiga
Chemical Industries Ltd. in Nairobi.
XI—GUIDE TO PROSPECTING IN KENYA
The frontispiece to this Bulletin is a simplified geological map of Kenya, the main
geological regions being separated as follows: —
Tertiary and younger sediments.
Volcanics.
Palaeozoic and Mesozoic sediments.
Bukoban System.
Basement System.
Nyanzian and Kavirondian systems.
A study of the table at the end of this chapter will show that certain minerals
occur in or with certain geological types. Therefore a knowledge of the rock types
will be of great assistence to the prospector.
NYANZIAN AND KAVIRONDIAN SYSTEMS
The compact area of these rocks in south-west Kenya includes a wide variety of
rock types of different ages, in fact the oldest known in Kenya. Most of Kenya's gold
has been found in this area, and these rocks are sometimes referred to as "Goldfields
Rocks". The gold is usually associated with quartz veins which are in turn associated
with the margins of granite masses. The quartz veins are frequently hidden by soil
and can only be discovered by careful loaming. Furthermore the gold is not usually
visible in the hand-specimen and has to be detected by panning or assaying. Gold
may also be found associated with murram deposits known as gossans. These gossans
should be carefully examined as, in addition to gold, copper has been found beneath
them. The Macalder Mine was a good example of this. Originally worked as a goldbearing gossan, the deeper the mine became the greater became the proportion of
copper and zinc, and the mine was subsequently worked mainly for its copper content.
Gold is also found in alluvials in this area and interest has been shown in lake beds in
the vicinity of the mouths of some rivers where low-grade deposits capable of largescale economic mining may occur. Small deposits of iron ore also exist in this area.
In the Gwasi Hills and at Homa there are alkaline igneous complexes, much younger
than the Goldfields Rocks, which contain pyrochlore and radioactive minerals.
26
BASEMENT SYSTEM
It will be seen from the map that there are four areas of Basement System rocks
exposed in Kenya, viz:
(1) An inverted " Y " running from Namanga and south of Voi through Kitui
and Machakos to north of Baragoi.
(2) Between Wajir and Moyale.
(3) South and west of Narok.
(4) WestPokot.
The rocks of the Basement System are very old, though younger than the goldfields
rocks, and have been subjected to intense heat and pressure. During this process
metamorphic minerals such as kyanite, graphite and corundum have been formed.
There are two types of intrusions in the Basement System that are of particular
interest to the prospector: —
(a) Ultrabasic and basic plutonic rocks
(b) Pegmatites
The localities of some of the ultrabasic and basic rocks are indicated on the map, but
there are many more. They frequently form rounded hills and also occur as sills.
The ultrabasic rocks particularly are dark coloured rocks and are often associated with
other rock types that are dark in colour. The prospector should make a point of
studying hand-specimens before going into the field. Asbestos, vermiculite and magnesite have been won from the ultrabasic rocks in Kenya, and platinum, copper and
nickel have been found in similar rocks in other parts of the world.
Pegmatites occur as narrow tabular deposits in which the minerals tend to be coarsely
crystalline, and often have a quartz core forming a ridge above the surrounding
country. They are a source of mica, beryl, columbite, microlite and other minerals.
Much work has been done in Tanzania on this type of deposit, and has been described
in the Tanzania Geological Survey Department's Bulletin No. 23, "Notes for Mica
Prospectors in Tanganyika" by D .N. Sampson. The Kenya prospector will find much
of interest in this booklet.
Much of Kenya's mineral production has been won from the Basement System and
it is probable that development will increase with improved transport facilities and
further prospecting.
BUKOBAN SYSTEM
In these rocks, which occur around Kisii, apart from soapstone only a little gold
and traces of cassiterite (tin ore) have been discovered.
PALAEOZOIC AND MESOZOIC SEDIMENTS
These are exposed in the south-east and north-east of Kenya. In the south near the
coast and associated with a series of faults they are the hosts of veins carrying lead,
zinc, silver and barytes, and in the extreme south in the Mrima area there are alkaline
igneous intrusions similar to those of the goldfields area. Pyrochlore, monazite and
rare-earths have been found. Nothing of economic importance has yet been discovered in the north-east, but it is possible that oil may occur in some of these rocks
at considerable depths.
VOLCANIC ROCKS
It will be seen that volcanics cover most of Rift Valley, Central and a large portion
of North Eastern and Eastern provinces. The volcanic rocks provide much building
material, but are also closely associated with several of Kenya's more important
mineral products which are found in the younger sediments described below. Carbon
dioxide gas and kaolin are also obtained from the areas of volcanic rocks. In the
central Rift Valley fluorite occurs in fault zones in the volcanics and underlying
Basement System rocks.
23!
TERTIARY AND YOUNGER SEDIMENTS
These can be subdivided into eastern and western portions. The eastern part which
includes much of the Tana and Lorian basins has produced little to date except
gypsum from the Garissa and Malindi areas. Beach sands have been investigated along
the coast between ihe Sabaki and Tana rivers and may prove a source of iron and
titanium minerals.
The western subdivision is of interest, particularly the sediments of the Rift Valley.
These are lake deposits and contain soda (Magadi) and diatomite, both of which are
valuable exports. The liquor of Lake Magadi also yields much common salt. In the
Amboseli area clay type minerals including meerschaum have been discovered. The
sediments west of Lake Rudolf contain small uneconomic showings of gypsum and
meerschaum.
The foregoing gives a general idea of the various areas, but for more detailed information regarding occurrences of particular minerals the prospector should consult
Bulletin No. 11 of the Geological Survey of Kenya, Minerals of Kenya by C. G. B.
Du Bois, and also the geological reports dealing with the particular area in which the
prospector is interested.
28
MINERALS AND VALUABLE ROCKS FOUND IN KENYA AND THE ROCKS WITH WHICH THEY ARE ASSOCIATED
(The more important minerals and rocks are shown in capitals: those not yet worked are indicated by parentheses)
Metamorphic
Rocks
Ultrabasic Rocks
Pegmatites
Goldfields
Rocks
Corundum
(Diamonds)
Dolomitic
limestone
Asbestos
Chromite
Corundum
(Diamonds)
(Garnierite)
Amazonite
(Amblygonite)
Beryl
(Bismuth)
Columbite
(Davidite)
(Euxenite)
(Arsenic)
Ballast
Brick Clays
(Cassiterite)
(Cobalt)
FLUORITE
N)
VC
Garnet
Gold
GRAPHITE
(llmenite)
Kaolin
KYANITE
LIMESTONE
(Manganese)
MARBLE
Rubies
(Rutile)
SAPPHIRES
(Sillimanite)
WOLLASTONITE
MAGNESITE
(Olivine)
SAPPHIRES
VERMICULITE
FELSPAR
(Fergusonite)
(Kyanite)
(Lepidolite)
MICA
(Microlite)
(Monazite)
Quartz crystals
(Samarskile)
(Zinc spinel)
COPPER
(Diamonds)
(Fluorite)
GOLD
(Iron ores)
(Molybdenite)
Pyrite
SILVER
SOAPSTONE
(Zinc)
(Scheelite)
Alkaline Igneous
Complexes
Older Sediments
Volcanic Rocks
Younger Sediments
(Apatite)
BALLAST
BARYTES
BALLAST
BUILDING STONE
CARBON DIOXIDE
FLUORITE
KAOLIN
(Alum)
Bentonitic Clays
Brick-earths
LIMESTONE
(Manganese)
(Monazite)
(Nepheline)
PYROCHLORE
RARE-EARTHS
(Wollastonite)
(Cinnabar)
(Gypsum)
LEAD
Limestone
SHALES
SILVER
ZINC
(Perlite)
Pozzolana
PUMICE
ROADSTONE
(Sulphur)
CLAYS
DIATOMITE
GUANO
GYPSUM
(llmenite)
LIMESTONE
Manganese
MEERSCHAUM
(Monazite)
(Nitre)
Pigments
(Rutile)
SALT
SAND (incl. glass sand)
(Sodium Bi-Carbonale)
Sodium Fluoride
TRONA
(Zircon)
APPENDIX I
READING LIST
Bernewitz, M. W. von.—Handbook for Prospectors and Operators of Small Mines.
McGraw-Hill Book Co. Inc., London. This book covers a wider field than the
present booklet and includes detailed descriptions of ore deposits in many parts
of the world. It also deals with the working of small mines. Although written
by an American for Americans it is nonetheless a most useful book for the
Kenya prospector.
Davidson, C. F.— A Prospector's Handbook to Radioactive Minerals. H.M. Stationery
Office, London. A useful addition to the prospector's library.
Denver Equipment Handbook.—Denver Equipment Co., 1400, 17th Street, Denver 17,
Colorado. This contains detailed information on milling and treatment useful
to the small mine operator.
Fersman, A. Ye.—"Oenchemical and Mineralogical Methods of Prospecting for Mineral
Deposits" U.S. Geological Survey, Circular 127.
Holmes, A.—Principles of Physical Geology. Thos. Nelson & Sons Ltd., London. An
interesting and well illustrated book which will give the prospector a better
understanding of geological principles.
Imperial Chemical Industries Ltd.—Gold Extraction for the Small Operator. Spottiswoode, Ballantyne & Co. Ltd., London. This book is almost essential to the
operator of a small gold mine.
Lahee, F. H.—Field Geology. Sixth Edition, 1961. Includes chapters on mineral
deposits and geophysical prospecting.
Pryor E. J.—Mineral Processing. Mining Publications Ltd., Salisbury House, London,
E.C. 2. This book gives detailed information on the treatment of minerals and
although it is intended for the mining engineering student there is much that"
is helpful to a small mine operator.
Read, H. H.—Rutley's Elements of Mineralogy. Thos. Murby & Co., 40, Museum Street,
London, W.C. 1. This or a similar book is almost essential for mineral
identification.
Sampson, D. N.—Notes for Mica Prospectors in Tanganyika. Bulletin No. 23, Geological Survey of Tanganyika. Government Printer, Dar es Salaam. A useful guide
to pegmatites. Most of the information is applicable to Kenya.
Truscott, S. J.—Mine Economics. Mining Publications Ltd., Salisbury House,
London, E.C. 2. This is also intended for the mining engineering student rather
than the prospector but it gives a clear indication of how mining properties are
valued and also information on sampling which is of value to the latter.
Watts, W. W.—Geology for Beginners. Macmillan and Co., Ltd., London. A useful
book on simple geology
30
APPENDIX 2
GLOSSARY OF TERMS
Words defined below are not necessarily used in the main text of this bulletin,
but the explanations given of words likely to be met when reading geological and
prospecting texts will be of value to prospectors.
Acicular.—Needle-shaped, such as some crystals of rutile.
Adamantine.—Like a diamond in lustre.
Alluvial.—Pertaining to alluvium.
Alluvium.—Gravel, soil, sand, silt and mud brought down by rivers and deposited in
valleys.
Amorphous.—Without form; applied to rocks and minerals having no definite crystalline structure.
Assay.—The determination of precious or base metals in ores. The method may be
either the wet or dry assay; the former by solution, the latter by fire.
Axis.—A straight line, real or imaginary, passing through a body.
Banded structure.—Term applied to rocks or veins having distinct layers or bands.
Bedrock.—Rock underlying surface gravels, soils etc.
Boss.—A dome-like mass of igneous rock solidified beneath the surface and laid bare
by erosion.
Bulkhead.—A partition of wood, rock and mud or concrete in mines for protection
against gas, fire and water.
Cam.—An eccentric projection on a revolving shaft, such as is used for lifting stamps
or for the valves in a car engine.
Cellular.—Cell-like, porous.
Cleavage.—Well defined parallel planes along which a mineral breaks.
Cohesion.—The force by which molecules of the same kind or of the same body are
held together so that the body resists being pulled to pieces.
Collar.—The timbering around the top of a shaft.
Columnar.—Column-like.
Complex.—An ore is called complex when it contains several minerals.
Concentrate.—The valuable minerals separated from gangue (waste) by any process
of concentration.
Conglomerate.—An aggregate of rounded and water-worn pebbles and boulders
naturally cemented together.
Contact.—The plane where two different formations meet. Ore-bodies frequently occur
along contacts.
Contact deposit.—A deposit at the contact of two unlike rocks, usually applied to an
ore-body at the contact between a sedimentary rock and an igneous rock.
Contorted.—Bent or twisted, such as folded strata.
Contour.—The outline of the surface of the ground with respect to its undulation.
Topographic maps and most geological maps include contour lines, which join
points of equal elevation and which define the shape of the surface of the area
mapped.
Debris.—Rock fragments, sand, earth, etc. which collect, for example, at the bottom
of a cliff; tailings.
Decomposition.—Breaking up or decaying.
Develop.—To explore an ore-body to determine its extent.
Dip.—The inclination of a structural rock-surface. The direction of dip is measured
at right angles to the direction of strike (q.v.) aiid the angle of dip is the angle
between a line on the surface in this direction and the horizontal in the same
vertical plane.
31
Distortion.—Twisting out of place or shape.
Dodecahedral.—Descriptive of a solid crystalline body, having 12 equal pentagonal
(five-sided) faces (e.g. garnet).
Effervescing.—Bubbling and hissing, such as occurs when dilute hydrochloric acid
acts on limestone.
Erosion.—The weathering and movement of rocks and debris derived from them.
Exfoliation.—The scaling off of the outer surface of a rock. The term when used in
relation to micaceous minerals indicates expansion perpendicular to the main
cleavage, an effect usually produced by heating (e.g. vermiculite).
Exposure.—Any part of a rock formation that can be seen; an outcrop.
Face.—Any part of a mine where work is under way; any plane surface of a crystal.
Fibrous.—Consisting of fibres, bundles of thread-like tissues.
Fissure.—A crack or opening in a rock. Fissure veins are those formed by mineral
m a t t e r heÀno Henoçited in Such cracks.
Float.—Loose or scattered pieces of rock or ore broken naturally from an outcrop.
Flotation.—A process of concentration in which separation- of minerals is effected by
causing some to sink in a liquid and others to float.
Footwall.—The lower enclosing wall of an inclined vein or other ore-body.
Forfeiture.—The losing of a right. Mining claims are liable to forfeiture when the
owner neglects to comply with the mining law.
Fracture.-»-The appearance of a freshly broken rock or crystal surface.
Gangue.—The valueless part of an ore-body. In a gold-quartz vein the quartz is of no
value and is the gangue.
Granular.—Made up of grains or granules, as crystalline rocks and most sediments.
Hanging wall.—The upper enclosing side or wall of an inclined vein or ore-body.
Homogeneous.—Consisting of similar parts, uniform.
Igneous.—Rocks of eruptive or volcanic origin that have solidified from the molten
state.
Intrusion.—A mass of igneous rock which, while molten, was forced into or between
other rocks.
Kibble.—A large bucket for hoisting ore.
Lava.—Molten rock-forming material occurring in and poured out from volcanoes.
Leach.—To dissolve metals from ore by draining the liquors downward. Gossan is the
result of leaching by nature.
Lode.—A vein reef.
Malleable.—Easily hammered when cold, e.g. lead, gold, silver.
Massive.—Without stratification, cleavage or schistosity.
Mesh.—One of the openings in a sieve or screen.
Metamorphism.—Any change in texture or composition of a rock caused by agencies
such as heat, fluids and pressure, either singly or together.
Mineral.—Any inorganic substance of regular and definite chemical composition.
Native.—Naturally occurring metal is termed native. Copper, gold, silver and platinum
are found native.
Non-metallic.—Not metallic, containing no metal, such as quartz sand. The term is also
applied to minerals used for purposes other than their metallic content might
indicate, such as kyanite and garnet.
Octahedron.—A solid crystalline body having eight faces. For a regular octahedron
the faces are equal equilateral triangles.
Ore-body.—Those parts of a vein that carry ore are ore-bodies or shoots.
32
Outcrop.—The outcrop is the exposed area of ore-body or rock which meets the surface. Sub-outcrop is an outcrop covered by soil or other superficial material.
Oxidize.—To unite with oxygen. Oxidation takes place when rocks and minerals are
weathered, and when materials are burned.
Placer.—A deposit of gravel or other superficial deposits from which gold or othei
valuable minerals can be obtained.
Platy.—Fracturing into thin plates.
Prismatic.—Resembling a prism: a solid whose bases or ends are any similar, equal
and parallel plane figures and whose sides are parallelograms.
Qualitative.—In testing ores, the determination of how many and what metals or
minerals are present.
Quantitative.—In testing ores, the determination of how much of each metal or
mineral is present.
Resinous.—Having the qualities or appearance of resin, a solid, inflammable substance
formed by exudation from certain trees.
Riffle.—A groove, channel or slat laid crosswise in a sluice-box rocker, to catch gold
or other heavy minerals.
Sectile.—Easily cut.
Specific gravity.—The ratio of the weight of any substance to that of an equal volume
of water. If a piece of the substance is weighed in air and then in water, its
specific gravity is obtained by dividing its weight in air by its apparent loss of
weight when weighed in water.
Specimen.—A selected piece of ore, rock, etc.
Strike.—The direction at any point on a structural surface, particularly a bedding
surface, of a horizontal line drawn on the surface through that point parallel to
a bedding, plane.
Stringer.—A narrow vein or veinlet.
Tails.—Material discarded after mineral dressing operations. Sometimes called
"tailings"
Terminations.—Ends (of a crystal).
Tetrahedron.—A solid crystalline body having four triangular sides.
Topography.—The physical features of a region, such as the hills and valleys.
Trapezohedron.—A solid crystalline body having 24 like faces, each face a trapezium
or a trapezoid.
Vein.—Any well defined mineralized zone, with or without payable ore-bodies or
shoots.
Vitreous.—Having a glass-like appearance or lustre.
Volatile.—Easily evaporated or converted into fume.
Weathering.—The process by which rocks affected by air, rain, plants, bacteria and
temperature decay and finally crumble into soil.
Width.—The true width of a vein is the thickness measured perpendicular to the
strike and dip. The thickness seen in a horizontal heading or trench is not
necessarily the true width (except in the case of vertical veins) and is known
as the apparent width.
33
APPENDIX
IDENTIFICATION TABLE FOR
(Minerals
NAME
COLOUR
COMPOSITION—MAIN
CONSTITUENTS
STREAK
asterisk)
HARDNESS
SPECIFIC
GRAVITY
REMARKS
Usually long crystals, columnar or
fibrous
Associated with kaolin and pyrite
Green
Vitreous
White
5-6
3-0-3-2
White, greyish or
reddish
White (tinged with
yellow, green, grey,
sometimes blue)
Vitreous-pearly
White
3f-4
2-6-2-8
ANOLESITE
Silicate of calcium,
magnesium and iron
Sulphate of potassium
and aluminium
Sulphate of lead
Adamantine,
vitreous
White
2*-3
6-1-6-4
Occurs in oxidation zones of lead
veins
ANTHOPHYLUTE
(ASBESTOS)
Silicate of iron
magnesium
Grey-brown, clovebrown, green
Vitreous
Uncoloured or
greyish
5H>
3-0-3-2
Found in crystalline schists
APATITE
Phosphate of calcium
Green-blue
Vitreous
White
3-2
Usually granular or in 6- sid d
prisms
ARSENOPYRITE
Sulphide of iron and
arsenic
Silvery white, verging
to steel grey
Metallic
Greyish black
AUCITE
Silicate of calcium, magnesium, ' iron and
aluminium
Black
Vitreous
White
AZURITE
Carbonate of copper
Blue
Vitreous
BARYTES
Sulphate of barium
White, inclining to
yellow, red, blue,
etc.
BAUXITE*
Hydrated oxide of
aluminium
BENTONITE
BERYL
ACTINOLITE
ALUNITE
»
that have not\yet been found in Kenya are marked by an
LUSTRE
3
MINERALS
and
5
5-9-6-3
Yields sparks and garlic odour when
struck slanting blows with steel
5-6
3-2-3-5
Crystals have 8-sided cross-sections, two perfect cleavages at
angles of almost 90° .
Blue
3H
3-8-3-9
Oxidation mineral that effervesces
vigorously in hydrochloric acid
of any strength and temperature
Vitreous-resinous
White
24-3*
4-3-4-6
Found commonly as gangue of
lead-zinc ores. Platy or granular
masses or either diamondshaped or rectangular crystals
Whitish,
greyish,
yellow, brown, red
Dull
Like colour
Silicate of calcium,
magnesium, aluminium and iron
Greenish or bluish
Dull
Light grey
Silicate of aluminium
and beryllium
Green, blue, yellow,
white
Vitreous
White
5T-6
1-3
7f-8
2-6
Chief ore of aluminium; occurs
massive. Completely soluble in
salt of phosphorus bead
21
A clay composed largely of montmorillonite. Swells greatly when
placed in water
2-6-2-8
Often embedded in quartz, with
mica and felspar. Usually in
6-sided prisms with flat terminations in pegmatite. Gem varieties
occur
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS—(Contd.)
COLOUR
BlOTIIB
Silicate of magnesium,
iron, aluminium and
potassium
Black, brown, dark
green
Pearly, vitreous
White
BisniTE
Oxide of bismuth
Straw yellow
Pearly
Like colour
BBMUTH
Bismuth
Silver white
Metallic
Silver white
BlSMUTHINITE
Sulphide of bismuth
Lead grey
Metallic
Like colour
BORAX*
Borate of sodium
White
Vitreous, dull
White
2-2*
BORNIIE
Sulphide of iron and
copper
Reddish to brownish
Metallic
Greyish black
3-31
4-9-5-4
Associated with chalcocite.Usually
massive. Quickly tarnishes with
iridescence
Jjj
BOURNONITE
Sulphide of lead,
antimony and copper
Steel grey to iron
black
Metallic
Like colour
21-3
5 -7-5 -9
Occursfine-grained,massive, brittle
BRUCITE
Hydrated oxide of
magnesium
White inclining to
grey blue, green
Pearly, vitreous
White
21
2-4
Associated with serpentine. A
secondary mineral
CALCITE
Carbonate of calcium
Colourless, white, and
shades of many
other colours
Vitreous
White
3
2-7
Massive and 6-sided pointed or
prismatic crystals. Effervesces
vigorously in hydrochloric acid
of any strength or temperature
CARNOTITE*
Uranate and vanadate
of potassium
Yellow
Vitreous, dull
Yellow
H
5
Powder or earth in sandstone.
Often concentrated around petrified wood. Radioactive
CASSITERITE
Oxide of tin
Brown, black, red
Adamantine
White, light
brown
6-7
6-8-7-1
Massive, or squarish crystals
CELESTITE*
Sulphate of strontium
White, often slightly
bluish, sometimes
reddish
Vitreous
White
3-3*
3-9-4-0
Occurs in veins with metallic ores
also in sediments
CERUSSITE
Carbonate of lead
White, grey
Adamantine
White
3-31
6-5-6-6
Oxidized mineral.
Effervesces
vigorously in concentrated or
boiling dilute hydrochloric acid
LUSTRE
STREAK
HARDNESS
SPECIFIC
GRAVITY
REMARKS
COMPOSITION—MAIN
CONSTITUENTS
NAME
2-7-3-1
Mica, cleaves easily into thin,
flexible and elastic plates
41
4-4
Of secondary origin resulting from
oxidation
21
9-7
Occurs native with ores of cobalt
and nickel. Brassy tarnish
2
6-4-6-5
Occurs in the form of thin coatings
21-3
1 -7
Sweetish alkaline taste
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS -iConnl.)
NAMÜ
COLOUR
COMPOSITION---MAIN
LUSTRE
STREAK
CONSTITUENTS
HARDNESS
Si'i.iiiic
GRAVITY
Rl.MAKKS
CHALCOCITE
Sulphide of copper
Dark grey
Metallic
Like colour
2J-3
5-5-5-8
Highly polished surface when cut.
Tarnishes easily
CHALCOPYRITE
Sulphide of iron and
copper
Brassy yellow
Metallic
Greenish black
-M-4.
4-1-4-3
Softer than pyrite. Often occurs
with pyrite, galena, sphalerite
CHERT
Silica
Black, brown, red,
yellow, white
Subvitreous
White
61-7
2-6
Occurs as nodules in sediments,
sometimes in volcanics
CHROMITE
Oxide of iron and
chromium
Black to
black
Submetallic
to
metallic, sometimes vitreous
Dark brown
51
4-1-4-9
Grains sometimes look like black
glass. Often occurs in serpentine
CHRYSOCOLLA
Hydrated
copper
silicate
of
Blue, green
Vitreous, dull
White
2i
2-0-2-2
Adheres to dry tongue,
important ore of copper
CHRYSOTILS'
Hydrated silicate
aluminium
of
White, greenish
Silky or
metallic
White
3-3+
2-1-2-6
The best asbestos. Masses of tough
usually parallel, slender fibres
CINNABAR
Sulphide of mercury
Red
Adamantine,
submetallic
Scarlet
2-2+
8-0-8-2
The only important ore of mercury
COBALTITE
Sulph-arsenide of cobalt
Silver white, steel grey
Metallic
Greyish black
5+
6-0-6-3
Granular or in crystals like pyrite.
Often with erytlirite
COLUMBITE
Columbate and tantalate
of iron and manganese
Iron black
Submetallic
Dark red to black
6
5-3-7-3
Brittle, flat, elongated
COPPER
Copper
Copper red
Metallic
Copper red
CORUNDUM
Oxide of aluminium
Blue, red, yellow,
brown, grey, almost
white
Vitreous,
adamantine
White
9
COVELUTE
Sulphide of copper
Dark blue
Submetallic
Black
H-2
CROCIDOLITE
Silicate of sodium and
iron
Blue or green
Silky, dull
Like colour
4-5
CUPRITE
Oxide of copper
Red
Adamantine
Red
3i-4
brownish
dull
silky
to
2+-3
8-8
an
crystals
3-9-4-1
Tarnishes easily. Ductile and
malleable
In 6-sided crystals and masses that
tend to break in three directions
at nearly 90° to each other. Gem
varieties (ruby, sapphire)
4-6
Platy or granular massive-. Turns
purple when moistened
3-2-3-3
5-9-6-2
Fibrous masses. It is a valuable
type of asbestos
An oxidation mineral. Often in
crystals—usually octahedrons
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS—{Contd.)
NAME
•^
COMPOSITION—MAIN
CONSTITUENTS
COLOUR
LUSTRE
STREAK
HARDNESS
10
DIAMOND
Carbon
Colourless,
white,
grey, pale shades of
yellow, red, green
blue, occasionally
black
Adamantine,
greasy
Ash grey
DIATOMITE
Hydrated silica
White, grey, yellowish
Earthy
White to grey
DOLOMITE
Carbonate of magnesium and calcium
White, often tinged
with yellow and
brown
Pearly to vitreous
White
EPIDOTE
Silicate of aluminium
iron and calcium
Green, yellow green
brownish green,
black
Vitreous
White, greyish
EUXENITE
Columbate and tantalate
of titanium, uranium
and rare earths
Brown to black
Glassy when
fresh
Yellowish, greyish, reddish
brown
FELSPAR
Silicate of aluminium
with potassium,
sodium, calcium,
barium
Colourless,
white
cream, pink, green
Vitreous
White
FERCUSONITE
Columbate and tantalate
of rare earths
Black to brown
Glassy
Pale bruwn
FLUORITE
(FLUORSPAR)
Fluoride of calcium
Alt colours
Vitreous
White
GALENA
Sulphide of lead
Lead grey
Metallic
Lead grey
GARNET
Silicate of calcium,
aluminium, iron,
manganese, chromium
Silicate of magnesium
and nickel
Red, brown, yellow,
green
Vitreous
While
Green
Dull, greasy
Greenish white
GARNIERITE
SPECIFIC
GRAVITY
REMARKS
3-5
Occurs in crystals (usually rounded
octahedrons) in a basic igneous
rock, and in placers. Gem
varieties
2-2
Roughens glass. Uniformly very
fine texture and light in weight
3i-4
2-8-2-9
Sometimes in crystals with curved
faces, usually massive. Closely
resembles calcite but effervesces
only with hot acid
6-7
3-2-3-5
Brittle; usually granular
54-6*
5-0-5-9
Nests or pockets in pegmatites.
Radioactive
2-3
Found in most igneous and metamorphic rocks. Prominent, in
pegmatites
5-5-6-0
In pegmatites; less commonly in
placers.
Usually
externally
coated with bun to pinkish
clay-like material
30-3-3
Octahedral cleavage. Brittle
54-6
24-3
7-4-7-6
Very brittle Cubic cleavage
(<\-V[
3-2-4-3
Often as dodecahedral crystals, in
schists or metamorphosed limestone. Gem varieties
2-4
Amorphous. A source of nickel.
Occurs with serpentine, chromite
2-4
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS—(Contd.)
NAME
COMPOSITION—MAIN
CONSTITUENTS
LUSTRE
COLOUR
STREAK
GAYLUSSITE
Hydrated sodium calcium carbonate
White
Vitreous
White
GOLD
Gold
Golden
Metallic
Golden yellow
GRAPHITE
Carbon
Black
Submetallic
GYPSUM
Sulphate of calcium
White, red, brown,
yellow, blue
HALITE
Chloride of sodium
White
HEMATITE
Oxide of iron
Steel grey, black, red, Metallic dull
submetallic
Red, reddish
brown
HORNBLENDE
Silicate of calcium, magnesium, aluminium,
alkalis and iron
While, green, black
Vitreous
ILMENITE
Oxide of
titanium
Iron black
KAOLIN
(CHINA CLAY)
Hydrated silicate
aluminium
KYANITE
HARDNESS
SPECIFIC
GRAVITY
REMARKS
2-3
1-9
Saline residue, commonly found in
lake sediments
2T-3
15-6-19-3
Malleable and sectile. Does not
tarnish
Dark grey, iron
black
1-2
21-2-2
Soft, marks paper, feels greasy
Vitreous
White to grey
11-2
2-3
Earthy, fibrous, scaly and crystals
with perfect cleavage in one
direction
Vitreous
White
2|
2-1-2-6
Natural table salt. Perfect cubic
cleavage
5f-6i
4-9-5-3
Becomes magnetic when heated
under reducing conditions
White
5-6
2-9-3-4
Crystals have 6-sided or diamondshaped cross-sections. Two
perfect cleavages at angles of
about 124°
Metallic,
submetallic
Brown
5-6
4-5-5-0
Weakly magnetic. An ore of
titanium
White, grey, yellowish
Earthy
White
2-2J
2-6
Alteration product of felspars
Silicate of aluminium
Blue, white,
green, black
Vitreous pearly
White
4-7
On different
faces
3-6
Bladed crystals with flat cleavage
surfaces that are easily scratched
longitudinally but not transversely
LEPIDOLITE
Silicate of aluminium,
potash and lithium
Red, lilac, white
Pearly
White
2f4
2-8-3--3
A mica withflex:w>le,elastic cleavage plates, usually in pegmatites
LIGNITE
(BROWN COAL)
Carbon
Brown to black
Dull
to
vitreous
sub- Like colour
1-2
1-1-1-3
Occurs as beds and lenses in
sedimentary rocks.
LIMONITE
Hydrated oxide of iron
Brown, yellow
Silky, often sub- Yellowish brown
metallic
5-5J
3-6-4-0
Massive, fibrous or porous. Magnetic after fusing
iron
and
of
grey
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS—(Contd.)
NAME
COMPOSITION—MAIN
CONSTITUENTS
COLOUR
LUSTRE
STREAK
HARDNESS
REMARKS
SPECIFIC
GRAVITY
LlNNAEITE*
Sulphide 'of cobalt
Steel grey
Metallic
Blackish grey
4-8-5-0
Copper-red tarnish
MAGNESITE
Carbonate of magnesium
White, yellowish
brown
Vitreous
White
•3 M i
31
Effervesces vigorously in hot concentrated hydrochloric acid
MAGNETITE
Oxide of iron
Iron black
Metallic,
submetallic
Black
5±-6±
5-2
Strongly magnetic
MALACHITE
Carbonate of copper
Green
Silky
Green
3M
40
Oxidation mineral. Effervesces
vigorously in hydrochloric acid
MANGANITE
Hydrated
oxide
manganese
of
Iron black, steel grey
Submetallic
Reddish brown
4-2-4-4
Hardness and streak are distinctive
MEERSCHAUM
Hydrated silicate
magnesium
of
White
Earthy
White
1-2
In beds and irregular masses in
alluvial deposits
MICROLITE
Tantalate of calcium
Pale yellow to brown
rarely hyacinth red,
olive green
Resinous
Pale yellowish or
brownish
5i
5-0-6-0
In pegmatites. Often with lithium
and barium minerals
MOLYBDENITE
Sulphide of molybdenum
Lead grey
Metallic
G r e e n i s h grey
on
porcelain,
bluish grey on
paper
l-H
4-7-4-8
Feels greasy
MONAZITE
Phosphate of the cerium
(rare earth) metals,
thorium and silica
Yellow, brown, red
Resinous
White
5-5i
4 9-5-3
Rounded grains often occur with
gold, chromite, iron
MUSCOVITE
Silicate of potassium
and aluminium
Colourless, yellowish
brown, violet, green
pink
Vitreous, pearly
White
2-2±
2-8-3 -0
Cleaves easily into very thin, elastic
flexible leaves
NEPHELINE
Silicate of sodium and
aluminium
White, yellowish,
green, bluish grey
red
Vitreous greasy
White
5i-6
2-5-2-7
Widely distributed in
igneous rocks
OLIVINE
Silicate of iron and
magnesium
Green
Vitreous
White or
yellowish
6i-7
3-3
Also called chrysolite
OPAL
Hydrated silica
All colours
Greasy, vitreous
White
5i-6i
1-9-2-3
Smooth curving fracture
Si
4
2-2i
alkaline
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS-{Contd.)
NAME
COMPOSITION—MAIN
CONSTITUENTS
COLOUR
LUSTRE
STREAK
HARDNESS
SPECIFIC
GRAVITY
REMARKS
PÊNTLAND1TE*
Sulphide of iron and
nickel
Light bronze yellow
Metallic
Light bronze
brown
PLATINUM
Platinum
Tin white, steel white
Metallic
Shiny grey
41
PSILOMELANE
Hydraled oxide of manganese with barium
and alkalis
Black
Submetallic, dull
Black, brownish
black
5-6
PYRITE
Sulphide of iron
Pale brass yellow
Metallic
Greenish brownblack
6-61
PYROCHLORE
Columbate of calcium
Yellow, brown
Resinous
Light brown,
yellow brown
5-51
4-0-4-5
In syenites, granites, carbonatites,
etc.
PYROLUSITE
Oxide of manganese
Black, dark grey
Metallic, dull
Black, blue black
2-21
4-8
Soils fingers. Hardness and streak
are distinctive
Sulphide of iron
Bronze yellow
coppery
to
Metallic
Greyish black
31-41
4-6
The only magnetic sulphide and
therefore distinctive
QUARTZ
Silica
Colourless,
yellow,
brown, red, green
blue, purple, black
Vitreous
White
REALGAR
Sulphide of arsenic
Red, orange-yellow
Resinous
Red to orangered
11-2
3-6
Usually associated with orpiment.
Sectile
RHODOCHROSITE
Carbonate of manganese
Usually red
Vitreous, pearly
White
31-41
3-5-3-6
Blackens on exposure. Effervesces
vigorously in hot concentrated
hydrochloric acid
RHODONITE
Silicate of manganese
Brownish red, flesh
pink
Vitreous dull
White
51-61
3-4-3-7
Occurs in various manganese orebodies
RÜTTLE
Oxide of titanium
Brown, red, black, etc.
Adamantine,
submetallic
Light brown
6-61
4-2
Commonly in crystals with longitudinally grooved faces, or
needles or hair-like
SAMARSKITE
Columbate of rare earths
Black to brown, liver
Glassy when fresh
Dark reddish
5-6
5-6-5-8
Similar to euxenite,
o
PYRRHOTITE
31-4
7
4-6-5 0
Associated
with
pyrrhotite,
millerite, chalcopyrite, etc.
14-19
Sometimes slightly magnetic. Often
occurs with chromite
3-7-4-7
50
2-65-2-66
Either powdery (wad) or has
mooth, curving fracture
Often in crystals that are cubic or
a form with 5-sided faces
Common in 6-sided prisms with
pointed terminations. Gem
varieties
Radioactive
APPENDIX 3
IDENTIFICATION TABLE FOR MINERALS—(Contd.)
NAME
COMPOSITION—MAIN
CONSTITUENTS
SCHEELITE
Tungstate of calcium
White,
white,
etc.
SERPENTINE
Hydrated silicate
magnesium
SlDERITE
LUSTRE
COLOUR
yellowish
brownish,
STREAK
HARDNESS
SPECIFIC
GRAVITY
REMARKS
Vitreous
adamantine
White
41-5
5-9-61
Weight, hardness and uneven fracture are distinctive.
Green, blackish green,
yellow, white
Wax-like, silky
White
2i-4
2-5-2-6
Feels smooth and
slightly greasy
Carbonate of iron
Grey, brown, brownish red
Vitreous, pearly,
dull
White
3i-4
3-9
Magnetic after heating. Effervesces
vigorously in hot, concentrated
hydrochloric acid
SlLUMANITE
Aluminium silicate
Green, grey, brown
Vitreous
White
6-7
3-2
Usually in long slender crystals in
metamorphic rocks
SILVER
Silver
Silver white
Metallic
Silver white
2f-3
10-5
Malleable and sectile. Tarnishes
quickly
SMITHSONITE
Carbonate of zinc
White, greenish, greyish or brownish
white, blue, brown
Vitreous, dull
White
5i
4-3-4-5
Effervesces vigorously
hydrochloric acid
SPHALERITE
( Z I N C BLENDE)
Sulphide of zinc
Yellow, brown, reddish, black
Submetallic,
resinous
Brown to light
yellow or white
3H»
3-9-4-1
Cleaves smoothly in six directions
at angles of 60°, 90° and 120°
SPINEL
Magnesium aluminate
Red, brown, black;
sometimes green,
blue
Vitreous
White
8
3-6
Occurs as crystals in igneous and
metamorphic rocks, and as
grains in alluvium
SULPHUR
Sulphur
Yellow
Resinous
White
2
20
Burns with a characteristic odour
TALC
Hydrated silicate
magnesium
Green to white
Pearly
White
1-1*
2-7-2-8
Feels greasy
TANTALITE
Tantalate and columbate
of iron and manganese
Iron black
Submetallic, often
brilliant subresinous
Reddish brown
6
6 0-7-3
Iron and manganese content
variable. Very similar to
columbite
TENNANTITE*
Sulphide of arsenic and
copper
Steel grey, iron black
Metallic
Black, reddish
brown
3-4
4-4-4-5
Occurs granular massive or in
tetrahedral
or dodecahedral
crystals
TETRAHEDRITE*
Sulphide of copper and
'antimony
Grey to black
Metallic
Black, sometimes
brownish or
reddish
3-4
4-4-5-1
Like tennantite but has a darker
streak
of
of
sometimes
in
hot
APPENDIX
3
IDENTIFICATION TABLE FOR MINERALS—{Contd.)
NAME
COLOUR
LUSTRE
STREAK
HARDNESS
SPECIFIC
GRAVITY
TOPAZ
Fluo-silicate of
aluminium
Yellow, white, greyish,
greenish, bluish,
reddish
Vitreous
White
TORBERNITE*
Hydrous phosphate of
copper and uranium
Green
Pearly
Green, paler than
colour
2-2*
3-2
TOURMAUNE
Boro-silicate of aluminium, magnesium,
iron, calcium, etc.
Silicate of calcium and
magnesium
Hydrated sodium carbonate
Black,
red
Vitreous to
resinous
White
7-7*
3 0-3-2
White to dark grey
Silky
White
5-6
2-9-3-4
Grey to white
Vitreous
White
2*-3
Uranate of uranyl, lead,
usually thorium and
rare earths
Chloro-vanadate of lead
Grey, green brown,
velvet black
Submetallic
to Black, grey,
green
greasy or pitchlike and dull
White or yellow
Resinous
VERMICULITE
Silicate of magnesium,
iron, aluminium
Greyish to yellow,
brown, almost black
Talc-like
White
H
2-7
WlLLEMITE*
Silicate of zinc
Vitreous, dull
White or greyish
5*
3-9-4-2
WlTHERITE*
Carbonate of barium
White, green, yellow,
brown, red
White, greyish,
yellowish
Vitreous, pearly
White
3*
4-3
WOLFRAM
Dark grey, brownish
black
White to grey
Submetallic
Reddish, brown
nearly black
WOLLASTONITB
Tungstate of iron and
manganese
Calcium silicate
ZIRCON
Silicate of zirconium
Colourless, yellow
grey, brown
TREMOLITE
TRONA
6
COMPOSITION—MAIN
CONSTITUENTS
URANINITE
VANADINITE*
GPK (L)
blue, green,
Red, brown, yellow
Vitreous
Adamantine
White
White
8
3-4-3-6
2 1
5*
9 0-9-7
24-3
6-6-7-1
5-5*
7-2-7-5
41-5
2-8
7}
4-7
REMARKS
Often in prismatic crystals with
diamona-shaped cross-section
and a perfect
transverse
cleavage. Gem varieties
Mica-like square crystals. Occurs
with other uranium minerals as
coating on many types of rocks.
Radioactive
Usually in prismatic crystals, often
with triangular cross-sections.
Gem varieties
Perfect cleavages in two directions
at an angle of about 124°
Occurs as fibrous crusts in saline
lakes and bedded deposits in old
lake beds. Soluble in water
Of primary and secondary origin.
Radioactive
Crystals prismatic 6-sided. Sometimes in parallel groups
Expands to form worm-like agregates of plates on heating
(exfoliation)
Massive to granular. A valuable
zinc ore
Effervesces vigorously in dilute
cold, but not. in concentrated
cold hydrochloric acid. Effervescing fragment colours alcohol
flame light yellowish green
Often occurs in the same area as
cassiterite
Occurs in metamorphic rocks,
especially crystalline limestones
In sharp crystals with square crosssections, and as pebbles. Gem
varieties