Geoarchaeology and Archaeomineralogy (Eds. R. I. Kostov, B. Gaydarska, M. Gurova). 2008.
Proceedings of the International Conference, 29-30 October 2008 Sofia, Publishing House “St. Ivan Rilski”, Sofia, 244-247.
GENETIC INTERRELATION OF ORES, SLAGS AND NONFERROUS METALS FROM
ARCHAEOLOGICAL MONUMENTS IN UKRAINE
Tatjana Yu. Goshko1, Vyacheslav I. Manichev2
1Institute of Archaeology, National Academy of Sciences of Ukraine, 12 Geroiv Stalingrada Av., 04210 Kyiv, Ukraine;
[email protected]
2Institute of Environmental Geochemistry, National Academy of Sciences of Ukraine, 34a Palladin Av., 03680 Kyiv, Ukraine;
[email protected]
ABSTRACT. The field of science which studies the ancient nonferrous metallurgy in Ukraine has entered a new stage of investigation
characterized by the system analysis of all components connected to the production of copper and alloys on its basis. The problem includes, first of
all, a comparative analysis of substance composition of the whole technological chain: ore – slag – metal. The authors have generalized the data
concerning artefacts from the ancient centres of metallurgy in Ukraine and made a conclusion about their genetic interrelations that is determined
by their geochemical similarity for each separate metallurgical centre. New data are presented for the chemical composition of slags and metals.
That means that the type of melted metal (copper, bronze, brass) depends on the chemical composition of the ore. Ores with a high content of tin,
lead, arsenic and other components in small quantity were used for production of bronze. The so called dirty (impure) copper was melted from the
copper ores with a large amount of impurities. The conducted investigations give reason to suppose that the ancient masters did not use any
recipes when melting the so called alloys, since all the impurities were available in the raw materials. Experimental works of melting nonferrous
metal from the ores and mineral blends have confirmed the possibility to produce metals which can be related to bronzes as to their composition.
The basic problem for those who study the ancient metal of Ukraine is the lack of the data concerning mineralogical and geochemical composition
of deposits of the Carpathian-Balkan Region. The further solution of the problems connected with the establishing of geochemical correlation
between the composition of ancient metals and ore depositsq as well as with the further reconstruction of the paths of the ore supply to the
metallurgical centres is possible with the efforts of specialists from various countries.
International experience in studying ancient nonferrous
metallurgy resulted in a number of ideas concerning bronze
production process which have become generally accepted.
They were mainly reduced to the analogy with present
metallurgical process of nonferrous metal production. The
ancient masters-metallurgists were ascribed the level of
knowledge about ores and metals comparable to the present
knowledge. In particular, it is accepted that they could
purposefully produce bronze and other alloys, using different
formulas. That permitted metal with preset properties to be
produced. Such a viewpoint is still common among
archaeologists, which study bronze both in Ukraine and
beyond. Such ideas are based on the accumulation of a large
amount of data concerning chemical composition of old metals,
copper and bronze (Schubert, Schubert, 1967; Cernykh, 1966,
1976; Petrescu-DоmbovіŃa, 1977; Liversage, Pernicka, 2002).
Slags and ores from ancient foundry workshops were not
practically investigated (Págo, 1968). Since copper and bronze
were studied separately from ores and slags, it did not seem
possible to establish genetic interrelation between them.
investigation of nonferrous metal and stone material (slags,
ores) from various monuments in Ukraine. The ancient town of
Subbotiv was the first site (Demchenko et al., 2000). Results of
investigations of the above material confirmed their genetic
similarity, which meant uniformity in the sense of comparison
of chemical composition. The fact of ore presence in slags as
well as high amounts of tin, lead and arsenic in metal articles
was unexpected for the researchers. Similar content of such
metals impurities was found in small fragments of ore,
represented by malachite cover, and in small drops-inclusions
of metal in slag.
Further geological-chemical investigation of nonferrous metal
and slags from other ancient centres of nonferrous metallurgy
(Belsk, Kamenka-Dnieper and Olbia site of ancient towns) has
been carried out. In all cases the obtained results were
identical. This meant that in the artefacts of the studied foundry
workshops (in bronze and slag) the researchers had found
impurities of the same metals. Tin, lead, zinc, arsenic, silver,
and other impurities were found most often. The quantitative
ratio of these impurities in slags and metal showed a
noticeable resemblance.
In the last decade, complex investigations of artefacts were
initiated in Ukraine that included the triad: metal – slag – ore.
The study was initiated by the famous Ukrainian archaeologist
Dr. V. I. Klochko. A group of different specialists, including
geologists and metal physicists, has carried out the
The results which we have obtained permitted the conclusion
that the chemical composition of copper and bronze depends
more on the initial composition of ore rather than on the
244
formulas chosen by the metallurgists. It should be specified
that the question is not for slags which can be part of the
foundry hearth but for the ore slags. Thus the impurities proved
to be natural, which was not known by the metallurgist.
Absence of direct chemical correlation between metal and
functional purpose of the object is one of the arguments for the
above fact. As shown by a great number of spectral analyses
(Table 2), a considerable spread of quantitative composition of
impurities takes place in bronze and copper. For example, the
content of tin varies from a few to 30% and above. It should be
noted that such a high content of tin is absent in the
contemporary classification of bronzes. We are sure that the
chemical composition of ores determines the type of bronze,
while slags are the binding link between them. Possible
interrelation between the composition of ores and metal was
noticed by a number of authors, including contemporary
scholars (Galibin, 1991).
A detailed investigation of slags and ores from ancient
foundry workshops simultaneously with the determination of
chemical composition of metal articles has been made.
Unfortunately, such material occurs very rarely. Since the ore
substance is subjected to different thermal effects in the
furnace, the relic areas of the initial ore are preserved in slag
only in some cases. In such cases one can observe mineral
composition, structure, texture and a number of other
peculiarities, including geochemical. As a result of uncomplete
output of the restored metal, it is sometimes observed in rather
considerable amounts in different forms of inclusions in slag
(up to 25%). As to their chemical composition the inclusions
can be similar or different even in the same slag sample. For
example, some inclusions in metal contain copper, others –
bronze.
Fig. 1. The inclusions of ore minerals in the metal ore ingot (Olbia, the IV
c. BC, Ukraine); needle-shaped (a) and tabular (b) tin-bearing minerals
We suppose that the ore raw material, which served to
produce the tin bronze, contained tin in the form of minerals
(cassiterite) or in the form of impurities in other minerals. The
availability of lead, zinc, arsenic and other minerals in ores
serves as a basis for production of the corresponding alloys.
Figure 1a-b demonstrates tin minerals in the primary ingot
melted from ore. A comparison of the chemical composition of
these mineral inclusions with the basic mass of metal is given
in Table 1. The presented results permit a conclusion to be
made for non-uniform distribution of tin in the sample volume,
as well as for the main role of tin-containing minerals in ore.
To find out interrelations between the chemical composition
of ore slags and metal articles, a considerable number of
artefacts has been analyzed. The spectral analysis of some of
them is presented in Table 2 (all the samples are characterised
by copper content).
Table 1
Chemical composition of a copper ingot from the ancient monument of Olbia (N1-3 – sites of pure metal; N4-6 – minerals inclusions
in the metal)
Metal
Metal
Metal
Mineral
Mineral
Mineral
inclusions
inclusions
inclusions
N1
N2
N3
N4
N5
N6
Cu
99.436
99.51
99.737
2.727
1.59
24.991
Ni
0.02
0.014
-
0.004
-
-
Fe
0
0
0.006
0.156
0.064
-
Zn
0.012
0.007
-
0.014
0.004
-
Ag
0.098
0.044
0.088
-
-
-
Pb
0.009
0
0.225
-
0.068
56.449
Sn
0.061
0.116
0.027
96.946
98.075
-
Sb
0.014
0.037
-
-
-
-
As
0.014
0.028
0.016
-
0.061
-
245
Table 2
Maximum content of metal impurities in copper ores, slags and copper articles from archaeological monuments in Ukraine (in %):1
– copper sulphate ore (Kartamysh, Donbas); 2 – malachite (Pilipchatino, Donbas); 3 – native copper (Donbas); 4 – copper ore slag
(Olbia); 5 – copper ore slag (Belsk site of the ancient town); 6 – copper artefact (Artemovsk museum); 7 – copper artefact (Bugskoe
IV); 8 – copper artefact (Dikiy Sad); 9 – copper artefact (Mylne I); 10 – copper artefact (Olbia)
1
2
3
4
5
6
7
8
9
10
Fe
10
0.4
0.5
4.8
1.2
1
0.04
0.1
0.06
0.2
Ni
0.015
0.004
0.035
0.03
0.03
0.01
0.15
0.3
0.03
0.04
Co
0.01
0.6
0.1
0.001
0.01
0.006
0.02
Cr
0.04
0.003
0.001
0.002
0.005
0.003
0.001
Cu
50
45
30
28
1
>90
>90
>90
>90
>90
Pb
0.3
0.008
0.015
0.6
0.25
0.2
0.25
0.8
0.02
0.35
Zn
0.006
0.004
0.01
0.4
0.01
0.15
0.05
0.006
Sn
0.0001
0.002
0.06
0.1
0.9
0.4
0.8
0.9
0.1
0.8
Mo
0.2
0.001
0.0001
0.0004
Sb
0.08
0.3
0.006
0.004
0.3
0.2
0.004
0.1
0.5
Bi
0.005
0.002
0.003
0.001
0.0001
0.005
0.002
0.004
0.002
0.01
As
0.9
0.05
0.1
0.1
0.1
0.3
4.75
0.2
0.15
0.6
The chemical composition of ores, slags and copper articles
is an evidence for the natural “contamination” with impurities,
with content reaching tenths of a percent.
In all cases, when the content of impurities exceeds 0.9-1%,
bronze is produced. Most difficult was to obtain bronze with
predetermined chemical composition, since this was only
possible with the help of modern technologies.
The ratio between copper and other metals is rather
unsteady in the polymetallic ores. As a rule lead, zinc, arsenic
or silver present in amount surpassing 2-3%. When melting
metal from such ore an ancient metallurgist always received
bronze. A high content of metal impurities in copper and
polymetallic ores is reported in large number of geological
publications dedicated to different deposits, including
Ukrainian. In the majority of known genetic types of ores one
can observe a considerable variety of impurities which is
related to mineral composition and degree of change in
oxidation conditions. Malachite, a copper mineral, can serve as
an example. In some cases (Table 2) the content of impurities
in malachite is minimal and in other cases, as the malachite
example from the ancient town of Subbotiv, tin, lead and
arsenic impurities exceed 1.5%.
If one can accept that bronze and metal copper were
produced in antiquity directly from the ore, one can establish
the site of ancient deposits and the trade routes facilitating the
raw materials supply from a deposit to a consumer. But the
claim that bronze was produced by following a production
technology close to the contemporary one, undermines all
search for ancient ore mines and related metal articles.
This work is based on the exceptionally interesting facts
concerning archaeological monuments in Ukraine. Unfortunately, no data about analogous investigations in other
countries has been found. There are publications on the study
of mines (ores) and metals, but with lack of the intermediate
link – slags.
It is known from the data in the literature (Betekhtin, 1949),
that tetrahedrite, a mineral present in numerous copper
deposits, may contain the following elements (%): Cu – 50, Zn
– about 9, Ag – about 15, As – about 20, Sb – about 25, Bi –
about 4. This mineral is also known in copper deposits in
Ukraine. It is evident that such ore will be the basic ore in the
metallurgical process for producing bronze.
One may agree or disagree with the view or interpretation of
the data obtained from analytical investigations. But it is
evident that the problem cannot be solved without contact with
the world scientific community. It requires combining the efforts
of scientists from different countries, and first of all, those of
the Carpatho-Balkan Region.
Such investigations should be conducted jointly with geologists. The method of geochronology (mass-spectroscopy)
should be included among the new analytical methods.
Complex investigation of ancient metals, slags and ores with
the use of contemporary analytical methods of research
permits obtaining of objective information about the history of
development of the ancient nonferrous metallurgy.
To confirm this point of view, we have conducted
experimental works of melting nonferrous metal (copper and
bronze) from different types of ores, as well as from artificial
mineral blends. The ore was melted in electric furnace with
maximum heating temperature 15000C. The preparation
technology and the metal production process itself were
approximated as much as possible to the ancient ones, as they
are presented in archaeological publications.
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