276                  THE DIAMOND
	area of about 45 square miles, over which there is an alluvial deposit ranging from a few feet to 25 feet in depth. The company controls 65 square miles. They reported in the early part of 1906, that in 30 days they recovered from the rotaries over a surface 56 yards long, some diamonds, 3,320 carats of chrysoberyl, sapphire and ruby, and other precious stones which brought the total up to 7,470 carats, at the rate of 2.14 carats to the load. In the autumn of 1907 they re­ported 4,000 carats of diamonds and 44,000 carats of other gems won up to that time. The deposit is located in an open valley, about 6,000 by 3,000 feet, between ridges in the Somabula forest, and is watered by the Somabula river. At the head of the valley lies the great watershed of the Zambesi and Limpopo rivers. As the district has an elevation of about 4,000 feet, it seems probable that the source of the deposit exists somewhere in the neighborhood, in large diamondiferous chimneys similar to those of Griqualand West, the Orange River Colony, and the Transvaal. The gravel contains enstatite, olivine, ilmenite, burnt-garnets and mica, garnets, chrysoberyl, sapphires, rubies, amethysts, jasper, iron conglomerite, and diamonds. The presence of some of the softer stones suggests that the source from which the deposit came is not far dis­tant. It is probable that diamonds will be found north also, in Mashonaland, for Keane says in " Africa" (Vol. II, South Africa): "In 1894 a survey of the Labangwe affluent of the Zambesi gave indications of diamond-bearing ground." The Somabula alluvial is now practically deserted, as diamond pipes have been discovered lately at Bambesi and are being developed.