How Excavation of Blueground Yields Diamonds

The diamonds are found in what is called blueground, which when mined is about as hard as sandstone. After being excavated from the mines the blueground is conveyed to the floors--large flat areas--where it is left from three to six months, or more, to soften. These floors are very large, those of the DeBeers and Kimberley mines covering two thousand acres. The blueground on the floors is harrowed by steam traction engines to assist in pulverizing the ground. This, with the action of the sun and rain, finally disintegrates the material so that it can be taken to the washing machines or pulsators, as they are technically called. The yield of diamonds per load of blueground is very small, but by the careful and comprehensive methods used, practically no diamonds are lost and the total yield is very large.