Bit Of History's Ancient Mining

There's an old saying that states, "if it isn't grown, its mined". Nowadays, that could be rewritten to include agriculture as it too depends on mining. Even the simplest gardener uses a hoe and a shovel both of which use iron (steel). Modern large-scale agriculture depends on farm machinery, chemicals, and fuel all which are mining products, to feed the growing populations of the world. Let's look at when this all began.

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The ability to work metals was such a large step in world history that divisions in history are named for the prominent changes of applied metallurgy. These differences mark boundaries in civilizations including the Stone Age (a period lacking in metals), the Bronze Age, Iron Age, and to a lesser degree, the Steel Age. To early civilizations there were only 7 known metals including gold, silver, copper, tin, iron, lead, and mercury. Although alloys of different metals do occur in nature they are very rare leaving the above list as the prominent metals used in ancient times.

The chart above shows the history of metal working. To see how metal working affected other parts of civilization, think about agriculture. For instance, about the same time that the ability of working with iron increased so did the invention of the iron-tipped plough and the chain driven irrigation buckets around 1000BC. By 500BC, the magnetic compass came into use along with iron reinforced buildings. Great civilizations emerge including the founding of Rome and somebody must have thought they needed to guard against thieves in Egypt because the lock and key were invented around 1000BC.

The mining of gold by various cultures can give a mini view of the learning sequence of metallurgy. The Egyptians mined gold using slave labor in Nubia, literally the land of gold (nub). They pounded the ore into fine dust and washed away the lighter particles much the same way the '49er's washed stream gravels in California leaving the heavier gold behind. The Egyptians used sponges to help trap the particles of gold the way modern day miners use "miners cloth" to trap the flakes of gold. A Greek historian of the time named Strabo mentioned a similar method of recovering gold in Caucasus whereby a fleece from a sheep was used to trap the gold. This method of gold mining probably led to the origination of the story of Jason and the Argonauts chasing the golden fleece. Even the refining of gold ore comes from ancient times. The early goldsmiths invented the process now known as cupellation, where gold alloyed with other metals is refined by mixing it with salts, lead, and some carbon based material and burning or melting the mixture in a clay crucible. The gold would "sink" to the bottom and the slag composed of the other metals would be cleaned off leaving a relatively pure button of gold.

For many years, silver mining was controlled by Hittites in Asia Minor. Silver was so valued and rare in Egypt, that the value of silver was twice that of gold. It is believed that the first silver coins were struck by the Hittites. Just as fluctuating prices of metals have driven the mining industry in modern times, so did it in ancient times. One of the greatest deposits of silver in the Greek world was located at Laurium in Attica and when the price of silver was high about 500BC, the mine was extremely active. The price of silver dropped about 300BC and a corresponding drop in mining activity at Laurium occurred. This same cycle can be found throughout mining history such as the closing of mines in the late 1800's in the United States due to falling silver prices.

Copper was the first metal to be used in modern times for everyday implements but in the ancient world, pure copper was a rarity and its use depended on the ability to smelt sulfide ores. The earliest records of the smelting of copper appear around 2000BC and by 1000BC, King Solomon was using small quantities obtained near the Red Sea. The Romans introduced a "new" method of purifying copper called "poling" which used a pole of green wood to stir the melted ore. The green wood released air into the mixture acting somewhat like a modern day air blast. The Bronze Age is really the "copper/tin" alloy age as this is the basis of bronze metals. Although early bronze was found in the Taurus Mountains of Turkey sometime before 3000BC, the alloy here is believed to have been a naturally occurring product. The use of bronze is believed to have fallen off after the natural ore of the area was depleted. Another major site for bronze manufacturing was located at Erzgebirge in Bohemia. This area was famous for its bronze up until modern times. The addition of tin to copper to produce bronze by necessity increased the knowledge of combining metals to form new and stronger materials.

The advent of iron mining and iron processing is probably the greatest single event affecting the mining industry. The ability to manufacture items from iron and later steel, led to the exponential growth of modern, strong, tools and manufacturing. Although the Greek philosopher Homer called iron sideros, later Greek writers would give it the name of chalybs after the first Greek people thought to use iron known as the Chalybes. Again, the people monopolizing early iron uses appears to have been the Hittites around 1400BC. The Hittite empire collapsed around 1200BC and the working of iron became established throughout the ancient world including the Middle East, India, and Europe. Although early processing of iron ores was crude at best, relatively pure metal could be formed by simple hammering. The problem was that early furnaces could not reach the melting tempeture of 1380º F required to melt the ores to the molten state. Early on, the addition of carbon to iron was recognized as a way to increase the hardness of the metal. Some knives found in China dating from AD112 have an inscription stating that the blades were forged 30 times and higher quality knives were known to be forged 100 times or more. Forging added strength and carbon added hardness to obtain materials that could better protect and serve as tools.

The Bessemer converter is an invention that is used to remove excess carbon from melted iron using the process of blowing air through the molten material. Two different inventors, William Kelly and Henry Bessemer, simultaneously invented this blast furnace in the mid 1800's. Kelly noticed in 1847, the affects of a blast of air on molten iron. He built 7 models between 1851 and 1856 and applied for a patent in 1866 for his process after learning that Bessemer was working on the same type of process. Bessemer had already patented his early furnace in 1855.

As can be seen throughout the history of much of civilization, the understanding of the role that metals and metal processing have made to technology of all types has been one of the major foundations that ancient and modern people have built upon.

Reference: The History of Invention/from Stone Axes... by Trevor I. Williams

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