Mining Techniques
Mining Techniques
Before you can beat or smelt or cast copper, it must be taken from the ground. In the beginning of mining, people simply picked up pieces of copper or gold, two metals that have a distinctive color, are found in large masses, and can be worked with primitive tools such as stone axes and hammers.
As civilizations began to use and depend on metals, the amount of pure copper or copper minerals found right at the surface was not enough anymore. Other ways of obtaining copper had to be developed.
These earliest miners quickly realized that some
copper minerals exposed on the surface were the tip of a deposit
going down into the earth. Using stone, and later copper and
bronze implements, the miners dug down to follow the deposit. The
implements were crude picks, hammers, chisels and shovels. Since
no method of blasting was available, miners were confined to much
slower and more tedious methods of opening the rock wall or face.
The miners picked at loose stones with their tools. If no cracks
or loose stones were available, fire was used to create sudden
changes of temperature to crack the rock. Logs were piled against
the rock face, then set afire. When the rock was very hot, the
fire was quenched with water. Then miners used their tools to
pull out the loosened rock.
Sometimes the miners followed loose nuggets of ore in gravel, called placers. Some metals make placers better than others. Gold makes excellent placer deposits because it tends not to react with air or water. Copper placers are less common. Tin, needed for bronze, makes excellent placers, while silver rarely is found as a placer deposit. Sometimes the miners followed veins into the solid rock, called lode deposits.
In Egypt, a great interest in gold drove exploration
for mineral deposits south into Nubia (presently the nation of
Sudan). Mining technology also improved. Excavations of large
rooms underground, called stopes, were supported
by pillars of unmined rock, or even by stone walls. Torches and
oil lamps supplied a flickering, smoky light. Ventilation in
these underground workings was very poor.
Slaves, prisoners of war, and criminals were forced to labor in the mines. Skeletons of those killed by falling rocks have been found, left buried where they died. Children would carry the pieces of ore to the surface in baskets strapped to their back. Once the ore reached the surface, other people who were too frail to work underground sorted the ore into richer and poorer pieces. Ore was moved by caravan to trade routes on the rivers, the Tigris, Euphrates, and Nile.
Geology
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