262                        THE DIAMOND
	rates dropped to about $1.50 to $2.00 per hundred lbs. Wages fell. At present, they range in all the mines, from fifteen to twenty-five dollars per month and lodg­ing for natives, and sixty to one hundred dollars per month for whites in the mines and prospecting. All the diamond chimneys of South Africa contain the same kind of rock, now called kimberlite, and wher­ever that rock is found it contains more or less dia­monds. The hardness of it varies in different mines, but it usually grows harder with depth. For this reason open-cut workings have an additional advantage in cost over those operated on the underground system. In the underground workings, shafts are sunk in the reef about two or three hundred feet from the chimney, and tunnels cut from them into the kimberlite, which is run out on cars and hoisted to the surface. Taken from these low levels the rock is hard and not fit for the wash­ers. It is therefore spread out on " floors"; large level stretches of ground, and exposed to the weather. The rain and sun disintegrate the rock and make it friable. Six to twelve months are usually given to this opera­tion, though it is sometimes hastened by sprinkling and harrowing. Near the surface, the rock is softer and does not require any exposure. An open-cut mine saves this expense. The New Premier runs its diamondifer-ous material, which is unusually friable, direct from the mine to the washers, and as it is very much greater in extent than any other, it will have this advantage over the older mines for some time to come. While they are constantly increasing the depth and consequent cost of working, the Premier will simply spread itself over a greater area of workings, in material that will not re-