Panning for diamonds in Sierra Leone.
The word ‘Diamond’ has been derived from a greek word “adamas” , which means unconquerable. Diamonds are made of pure carbon and are so far the hardest natural substance known to man.
Diamonds are since long symbols of social status. Every famous diamond of the world has a sorrow tale to tell as many people have died to own it and many have died to steal it. These gems can be transparent, truculent white, yellow, green, blue, or brown. Diamonds have played a great role in many battles and have given birth to human tragedies.
Diamond was first discovered in India and Borneo in the river beds and later on in the eighteenth century in Brazil. In Africa they were discovered between December 1866 and February 1867 on the south bank of the Orange River. After the discovery, within 15 years the African mines produced more than what India had produced for the last 2000 years. This increase meant that the prices of diamond would not fall as there was a sharp decline in the production of Brazil.
Diamonds are found 150 Km. below the earth’s surface. The diamonds make their way up the surface captured within liquid hot rock or magma. Once they reach the surface diamonds can be found in volcanic pipes called kimberlite pipes or in loose mineral deposits called alluvial deposits.
Alluvial deposits are created by diamond pipe erosion and are easily excavated. They require very little financial capital to be invested in the removal. This is due to the fact that they are often found in riverbeds and along the coast and they do not require highly advanced mining techniques nor due they require a large amount of human capital. The simplest method of mining alluvial deposits is with a shovel and a pan. With this method diamonds and soil are shoveled into a hand held pan where they are separated by agitation and shorted by eye. More advanced methods of mining use large machinery that moves the alluvial in to large shorting pans that send different densities to smaller picking tables followed by a grease table. Since diamonds are mostly water repellent, they are sorted in alluvial deposits by using grease. While other minerals develop a water coding and slide of the grease, the water resistant diamonds stick to the grease and are collected. Mining kimberllite pipe requires a more advanced degree of mining technology and is more expensive. The first step in mining a kimberlite pipe is to dig the pit. In “open-pit” or “open-cast” mining, the layers of rock are dug up and eventually tunnels and pipe are build so the hard ore material can be removed with large hydraulic shovels and trucks. The hard rock is broken into pieces with shovels and other methods until the rock is small enough to be remove from the mine by truck. When the kimberlite ore is deep underground it must be removed by mining a series of underground shafts in the pipe that allow the ore to be carved off and make its way down the tunnel to a draw point. At these points the crushed ore is brought up to the surface for processing. Only about 20% of the world’s diamonds are taken from pipe mines, and the remaining 80% of diamonds are alluvial.
In 1866, the first diamonds in Africa were found. Before the discovery of diamonds in South Africa diamonds were very scarce and they were highly valued. Following the discovery of diamonds in Africa the production of diamonds increased tenfold in the next tens years.
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