MONTEREY PENINSULA COLLEGE
GEOLOGY 2
LAB 2: ROCK & MINERAL IDENTIFICATION
Common Rock-Forming and Economic Minerals & Igneous Rocks
Goal: To be able to determine a mineral’s physical properties and use those properties to identify common minerals in hand specimen or in a rock.
Examine the mineral specimens at the front desk.
apatite
gypsum
biotite
calcite
halite
corundum
hematite
K-feldspar
hornblende
plagioclase feldspar
magnetite
muscovite
fluorite
olivine
garnet
pyrite
graphite
quartz
1.
What is cleavage?
2.
Which minerals display cleavage?
3.
What is fracture?
4.
Are fracture and cleavage different? If yes, how?
5.
What is luster?
6.
What is a mineral’s streak?
7.
Why is streak sometimes useful?
8.
Why are some physical properties of a mineral considered diagnostic properties, while other properties are not?
talc
Look at the two types of feldspar; potassium feldspar (also called K-spar) and plagioclase.
9.
Describe or draw perthitic structure (k-spar).
10. Describe or draw striations (plagioclase).
11. Why is amber not a mineral?
12. …or volcanic glass?
13. …or synthetic ruby?
14. What is a distinctive and diagnostic property of halite?
15. …and hematite?
16. …and calcite?
17. …and magnetite?
18. Identify the unknown minerals numbered 1 through 12 (on the desks).
Use the attached worksheet. You will be able to use your notes (but not your book) on the rock & mineral ID quiz.
1.
4.
7.
10.
2.
5.
8.
11.
3.
6.
9.
12.
19. What are the two best ways to distinguish quartz from feldspar?
20. On Mohs’ hardness scale, where does glass fit in? (Give the number and the mineral closest in hardness to the object)
21. …and a steel pocketknife blade?
23. What is the chemical composition (formula) of feldspar?
22. …and your fingernail?
Is it fixed or variable?
MONTEREY PENINSULA COLLEGE
GEOLOGY 2
Examine the igneous rock specimens at the front desk.
granite
pumice
diorite
rhyolite
andesite
gabbro
basalt
obsidian
Assume the four most abundant minerals in this specimen of granite comprise 100% of the rock.
24. What are the four main minerals in this rock, and what are the percentages of each mineral?
25. How do you identify an igneous extrusive (volcanic) rock if the crystals are too small to identify?
26. How do the crystal sizes in extrusive rocks differ from the crystal sizes in intrusive rocks?
27. If pumice and obsidian are the same composition (both volcanic glass), what does their texture say about the
environment in which they formed?
28. What is the name of the large, whitish crystals (i.e. phenocrysts) in the specimen of andesite?
29. What is the most common type of igneous intrusive rock in continental crust?
…and igneous extrusive?
30. What is the most common type of igneous intrusive rock in oceanic crust?
…and igneous extrusive?
Answer the following questions from the video program titled Intrusive Igneous Rocks:
31. What are 2 or 3 origins of the heat within the earth?
32. Do all minerals in a rock crystallize at the same time?
33. Are magmas that form rocks in the ocean the same as the magmas that form rocks on/in the continents?
34. What is a xenolith?
35. What common 70’s icon does James Sadd use to model how a batholith might form?
Answer the following questions from the video program titled Minerals: The Materials of Earth:
36. Granitic rocks are mostly composed of what three common minerals?
37. …and basaltic rocks?
38. Four common rock-forming minerals comprise most rocks on earth and are the basis for classifying rocks.
39. What are these four minerals?
40. How does the mineral halite form?
41. If the two minerals, graphite and diamond, are both elemental carbon, then why are they so different?
42. What is the name of the type of bond in a diamond’s crystalline structure?
43. Electrically charged particles that join together to neutralize their charges and form an atomic structure are called _____ .
MONTEREY PENINSULA COLLEGE
GEOLOGY 2
Define the following:
mineral: A naturally formed, inorganic, homogeneous, solid crystalline
substance.
Rock: A naturally formed, consolidated material composed of grains or
crystals of one or more minerals.
Element
lithosphere
compound
magma
acicular
felsic
conchoidal
mafic
spherulitic
texture
tabular
composition
equigranular
pluton / plutonic
rhombic
foliated
vitreous
pegmatite
striation
porphyritic
perthite
aplite
MONTEREY PENINSULA COLLEGE
GEOLOGY 2
Name
A short list of some of the Earth’s common rock-forming and economic minerals:
Group
Class
Luster
Color
Streak
Hardness
BLU
5-6
6
7
5-7
3-3.5
6
5
3.5-4
5.5-6
5-6
3.5-4
3.1
2.6
4.2
3.6
2.9
2.8
3.2
2.95
6.1
3.3
3.8
BLK
3
1-3
6.5
7.5-8
2.5-3
3
4.5
2.3
3.6
2.8
3.0
5.7
3
2.5-3
3.5-4
2.5-3
6-7
2.5
2.5
2.5-3
7-7.5
9
2.72
5.7
4.2
3.0
3.5
2.4
8.1
8.9
2.63
4.0
VAR
GRN
VAR
10
5-6
3.5-4
3.5
3.3
2.85
VIT
VIT
BRN
GRN
5.5
6-7
3.4
3.4
Sorosilicate
VIT
VAR
4
3.19
Sulfide
Hydr/oxide
Native elem.
Native elem.
Nesosilicate
Sulfate
MET
ERTH
MET
GRSY
VIT
VIT
BLK
BRN
GLD
BLK
GRN
WHT
2.5
5-5.5
2.5-3
1-2
6.5
2
7.5
4.37
15-19
2.3
3.53
2.32
Halide
Hyro/oxide
Inosilicate
VIT
MET
VIT
COL
BLK
BLK
RED
2.5
5.5-6
5-6
2.16
5.26
3.2
Hydr/oxide
SUB
BLK
BRN
5.5-6
4.7
Inosilicate
VIT
VAR
6.5-7
3.4
Inosilicate
Tectosilicate
Nesosilicate
Nesosilicate
Sulfate
Tectosilicate
Phosphate
Carbonate
Sulfide
Inosilicate
Carbonate
VIT
VIT
VIT
VIT
VIT
VIT
VIT
VIT
MET
VIT
VIT
GRN
COL
VLT
BLU
WHT
GRY
VAR
VAR
SLV
BLK
BLU
Sulfate
Hydr/oxide
Cyclosilicate
Cyclosilicate
Phyllosilicate
Sulfide
VIT
ERTH
VIT
VIT
PRLY
MET
VAR
BRN
BLU
VAR
BLK
BRNZ
CALCITE
CHALCOCITE
CHALCOPYRITE
CHLORITE
CHLORITOID
CHRYSOTILE
CINNABAR
COPPER
CORDIERITE
CORUNDUM
Carbonate
Sulfide
Sulfide
Phyllosilicate
Nesosilicate
Phyllosilicate
Sulfide
Native elem.
Cyclosilicate
Hydr/oxide
VIT
MET
MET
PRLY
PRLY
SLKY
ADM
MET
VIT
ADM
VAR
BLK
BRNZ
GRN
GRN
GRN
RED
ORNG
BLU
VAR
DIAMOND
DIOPSIDE
DOLOMITE
PYRX
Native elem.
Inosilicate
Carbonate
ADM
VIT
VIT
PYRX
Inosilicate
FLUORITE
GALENA
GOETHITE
GOLD
GRAPHITE
GROSSULAR
GYPSUM
ACTINOLITE
ALBITE
ALMANDINE
ANDALUSITE
ANHYDRITE
ANORTHITE
APATITE
ARAGONITE
ARSENOPYRITE
AUGITE
AZURITE
BARITE
BAUXITE
BENITOITE
BERYL
BIOTITE
BORNITE
ENSTATITE
EPIDOTE
HALITE
HEMATITE
HORNBLENDE
AMPH
PLAG
GARN
PLAG
PYRX
MICA
GARN
AMPH
ILMENITE
JADEITE
PYRX
S.G.
BLK
GRY
BLK
RED
RED
BLK
YLW
GLD
BLK
MONTEREY PENINSULA COLLEGE
GEOLOGY 2
Name
Group
Class
KAOLINITE
KYANITE
Phyllosilicate
Nesosilicate
LIMONITE
MAGNETITE
MALACHITE
MICROCLINE
MOLYBDENITE
MONAZITE
MUSCOVITE
Luster
Color
ERTH
VIT
WHT
BLU
Hydr/oxide
ERTH
BRN
Hydr/oxide
Carbonate
Tectosilicate
Sulfide
Phosphate
Phyllosilicate
MET
VIT
VIT
MET
RSN
PRLY
BLK
GRN
VAR
BLK
BRN
BRN
NEPHELINE
Tectosilicate
GRSY
OLIVINE
OPAL
ORTHOCLASE
Nesosilicate
Tectosilicate
Tectosilicate
Streak
Hardness
S.G.
2-2.5
5-7
2.6
3.6
YLW
5-5.5
3.8
BLK
GRN
6
3.5-4
6
1-1.5
5-5.5
2-2.5
5.18
4.0
2.55
4.70
5.2
2.9
VAR
5.5-6
2.60
VIT
VIT
VIT
GRN
VAR
VAR
6.5-7
5-6
6
3.8
2.0
2.57
Sulfide
Nesosilicate
Phyllosilicate
Sulfide
MET
VIT
PRLY
MET
BRNZ
RED
BRN
BRNZ
6-6.5
7
1-2
4
5.02
3.51
2.8
4.6
QUARTZ
Tectosilicate
VIT
VAR
7
2.65
SERPENTINE
SILLIMANITE
SILVER
SPHALERITE
SPINEL
STAUROLITE
SULFUR
Phyllosilicate
Nesosilicate
Native elem.
Sulfide
Hydr/oxide
Nesosilicate
Native elem.
GRSY
VIT
MET
RSN
ADM
VIT
RSN
GRN
WHT
SLV
YLW
VAR
BRN
YLW
2-5
6-7
2.5-3
3.5-4
8
7-7.5
1.5-2
2.2
3.23
10.5
3.9
3.8
3.7
2.07
TALC
TITANITE
TOPAZ
TOURMALINE
TREMOLITE
TURQUOISE
Phyllosilicate
Nesosilicate
Nesosilicate
Cyclosilicate
Inosilicate
Phosphate
GRSY
ADM
VIT
VIT
VIT
ERTH
GRN
VAR
VAR
VAR
VAR
BLU
1
5-5.5
8
7
5-6
6
2.8
3.48
3.5
3.25
3.15
2.7
Nesosilicate
Sorosilicate
ADM
VIT
VAR
VAR
7.5
6
4.68
3.35
PYRITE
PYROPE
PYROPHYLLITE
PYRRHOTITE
KSPAR
MICA
KSPAR
GARN
AMPH
ZIRCON
ZOISITE
GRY
BLK
BLK
SLV
YLW
YLW
ABBREVIATIONS:
ADM
AMPH
BLK
BLU
BRN
BRNZ
COL
ERTH
GARN
GLD
Adamantine
Amphibole
Black
Blue
Brown
Bronze
Colorless
Earthy
Garnet
Gold
GRN
GRSY
GRY
KSPAR
MET
MICA
ORNG
PLAG
PRLY
PYRX
Green
Greasy
Grey
K-feldspar
Metallic
Mica
Orange
Plagioclase
Pearly
Pyroxene
RED
RSN
SLKY
SLV
SUB
WHT
VAR
VIT
VLT
YLW
Red
Resinous
Silky
Silver
Submetallic
White
Various
Vitreous
Violet
Yellow
>30% hbld
DIORITE
Mafic, <20% qtz, no K-spar
BASALT
Foliated: No visible micas
SLATE
Acid rxn
MARBLE
Fissile
Not powdered
Powdered
SHALE
LIMESTONE OR CALCITE
DOLOMITE
COARSE
>90% qtz, conchoidal frac.
fissile
SILTSTONE
SANDSTONE
CHERT
>20% rock fragments
LITHIC SANDSTONE
GLASSY
MEDIUM TO
COARSE
Unlayered, blocky
>20% feldspar
ARKOSE SANDSTONE
VERY
COARSE
MUDSTONE
>50% qrtz
QUARTZ SANDSTONE
MED.
Rounded clasts
CRYSTALLINE (INTERLOCKING CRYSTALS)
CONGLOMERATE
(often structured)
Angular clasts
Foliated:qtz+k-spar>>mica
GNEISS
METAMORPHIC
BRECCIA (Can also be volcanic)
Foliated: med. To coarse
SCHIST (with modifier)
FINE
Unfoliated, >90% qtz
FELSIC
QUARTZITE
VOLCANIC
(igneous extrusive)
Foliated: Visible mica, sheen
Vesicular (or frothy looking)
PUMICE
PLUTONIC
(igneous intrusive)
PHYLLITE
Solid, conchoidal fracture
Plag>k spar
Felsic, >20% qtz,
k spar>plag
Felsic, >20% qtz,
FINE
OBSIDIAN
DACITE
RHYOLITE
Int., <20% qtz, plag>>k-spar
>20% qrtz, plag>>>k-spar
TONALITE
COARSE
ANDESITE
>20% qrtz, k-spar>/=plag
<20% qtz, K-spar>>>plag
Plag>>>K-spar
<20% qtz,
>90% mafic or colored minerals
MAFIC
GRANITE
SYENITE
>30% pyrx
GABBRO
ULTRAMAFIC
MONTEREY PENINSULA COLLEGE
GEOLOGY 2
TEXTURE
CLASTIC/SEDIMENTARY/CHEMICAL
FINE TO VERY FINE
GRAINS
VISIBLE
MICROSCOPIC
(but not
distinguishable)
Any size grains
*ACID RXN?
COMPOSITION
* not including the cement between grains