How diamonds are mined...
We seldom think about how the diamonds we wear came to us. Natural diamonds, as opposed to synthetic diamonds
or diamond stimulants such as zircons, are mined from the earth. There are currently two methods of mining diamonds: pipe mining and alluvial mining.
When pipe mining is used, the diamonds are extracted from the earth through natural volcanic pipes. Typically, a very large area needs to be covered. An average of 250 tons of ore must be mined in order to produce a 1 carat gem quality polished diamond!
After the surface deposits have been exhausted, shafts are sunk into the ground alongside the pipes, and tunnels are driven into the deeper sections of the pipes. Blasting is used to dislodge the ore, which is then loaded by excavators into dump trucks, to be transported to the screening plant for sorting.
The alluvial mining process involves the extraction of diamonds from riverbeds and ocean beaches. Several million years ago, when the geological process creating diamonds first started, some diamonds were weathered out of the natural diamond pipes and carried vast distances to rivers and even into oceans.
To extract these diamonds from beaches, a wall is built to hold back the river water or sea surf. Up to 25 meters of sand is bulldozed aside to reach the diamond-bearing level. Once reached, the diamond-bearing earth is removed and transported to screening plants.
As with pipe mining, the sand is loaded onto a dump truck and transported to screening plants where the ore is sifted mechanically to separate the diamonds from the other materials. The manual sorting process determines whether the diamonds are of industrial quality, gemstone quality, or only good enough for use as diamond dust.
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