African Ruby: Gemstone Information
In 1973 American geologists Tim Miller and John Saul discovered ruby in Tsavo West National Park, in the Mangari area. As so often happens, facetgrade crystals were much less plentiful than heavily included cabochononly material. Crystals in some cases were well formed and would have made desirable collectors’ specimens had many not evaded the cabochon cutters and perhaps exporters. The Kenya government of the time appropriated the mines: though ownership disputes took time to resolve private owners eventually regained control and good-quality cabochon-grade and a few facet-grade crystals are being recovered. Most crystals are sent to Thailand for fashioning. Turkana and its vicinity in north-west Kenya produce dark, variously coloured sapphires.
Sapphires of various colours have been reported from Namibia. Blue sapphire has been found in the Beraketa region of Madagascar where itoccurs with feldspar; blue sapphire is also reported (extra Lapis English no. 1, 2001) from a skarn south-east of Andranondambo. Blue sapphire of moderate quality is found in some abundance in the Ilakaka river; the town of Ilakaka has become a major gemstone trading centre. Readers should consult Lapis for June 1999 for a paper by Karl Schmetzer on Madagascar corundum. Fancy sapphires (not ruby or blue sapphire) appear to be characteristic of African deposits. Crystals with a colour change (the colours varying) may become another African speciality. small deposits of corundum of various colours have been reported from the Somabulu forest in south-western Zimbabwe and a deposit of sapphire has been reported from a pegmatite and in alluvial gravels in north-eastern Zimbabwe. Dark blue sapphires have been found near Jauru, Mato Grosso, Brazil, and both ruby and sapphire in the Rio Mayo, a tributary of the Patia, and in the sands of the Platayaco, in the Caqueta area of Colombia.