Tin Deposits and the Early History of Bronze: Part 4
Previous chapters have focused on the mineralogically complex and
structurally simple silver-uranium-base metal vein deposits in the
Erzgebirge, such as Joachimsthal, which were relatively easy to find and
mine. We now turn our attention to the tin mines, which could not be
more different. The various deposit types exploited by the medieval
Saxon miners illustrate the sophisticated prospecting, mining, and
metallurgical skills that they had developed by the sixteenth century.
Today, tin is just another alloy metal, like titanium or beryllium, and
many geologists and mining engineers may never see a tin mineral outside
a museum. Until the appearance of hard steel during the Industrial
Revolution, tin held a similar strategic importance to that held by oil
today because it is a vital component of bronze. Bronze was used to
manufacture the first hard, corrosion- free metallic tools such as
shovels, axes, chisels, and hammers, as well as weapons, jewellery,
burial items, and bell metal. It became an indispensable commodity,
worth scouring the world for and going to war over, and it occupies a
special place in the history of mining, economic geology, agriculture,
warfare, art, and human development. Gold and silver could finance a
war, but bronze could win it. The metal is even mentioned several times
in the Bible; for example, "I will turn my hand upon thee, and purge
away thy dross, and take away all thy tin" (Isaiah 1:25).
The significance of metals has been well stated by Muhly (1988).
"Turning a hard rock into a softer and more useful metal was a unique
step in human development." To appreciate the historic importance of
Erzgebirge tin, we must quickly review the early history of copper and
bronze production and the first sources of tin. Because the production
of copper and bronze predate written records by many millennia,
deciphering the historical record by determining the source and age of
metallic artifacts has been the work of archaeologists. They have shown
that the first use of metals began in the part of the Middle East that
lies between the eastern end of the Mediterranean Sea, the Persian Gulf,
and the Black and Caspian seas, and forms the boundary between Europe
and Asia. It encompasses the mountainous parts of Turkey and Iran and
extends south into northern Iraq and northeast through Armenia, Georgia,
and Azerbaijan to the Caucasus Mountains. It is a mineral province that
contains abundant copper, silver, iron, and other base metals, but only
moderate amounts of gold and little tin. For additional geological
background and a review of metallurgical history, see Cathro (2000) and
Knauth (1974), respectively.
Archaeometric dating has shown that the first metalsmiths began working
with native copper about 9500 BC. After the native metal became scarce,
they discovered that copper could be produced from the associated
gossans by heating copper oxide, carbonate, and silicate minerals at a
high temperature in the presence of carbon. Further progress depended on
finding ways to produce higher furnace temperatures. The early smiths
soon discovered that the melting temperature of copper ore was lowered
and the metal became harder when the ore contained impurities, a lucky
advantage since they had no way to predict what contaminants were
present in the weathered ores. By about 6000 BC, they were able to smelt
copper from gossans formed from oxidized complex ores, and by about 4000
BC, they had learned to smelt silver-lead oxides. Bronze was produced by
about 3500 BC and poor quality iron by about 2700 BC. About 2500 BC, the
bronze technology began to spread northward into central and western
Europe and eastward to the Indus Valley civilization. It reached China
about 1500 BC.
rest at
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