AXINITE  , a

mineral consisting of a complex aluminium and calcium boro-silicate with a small amount of basic hydrogen; the calcium is partly replaced in varying amounts by ferrous iron and manganese, and the aluminium by ferric iron: the formula is HCa3BAl2(SiO4)4 . The mineral was named (from &eivrg an axe) by R . J. flatly in 1799, on account of the char- acteristic thin wedge-like form of its anorthic crystals . The colour is usually clove-brown, but rarely it has a violet tinge (on this account the mineral was named yanolite, meaning violet stone, by J . C . Delametherie in 1792) . The best specimens are afforded by the beautifully developed transparent glassy crystals, found with albite, prehnite and quartz, in a zone of amphibolite and chlorite-schists at Le Bourg d'Oisans in Dauphine . It is found in the greenstone and hornblende-schists of Batallack Head near St Just in Cornwall, and in diabase in the Harz; and small ones in Maine and in Northampton county, Pennsylvania, U.S.A . Large crystals have also been found in Japan . In its occurrence in basic rather than in acid eruptive rocks, axinite differs from the boro-silicate tourmaline, which is usually found in granite . The specific gravity is 3.28 . The hardness of 62-7, combined with the colour and transparency, renders axinite applicable for use as a gem-stone, the Dauphine crystals being occasionally cut for this purpose .

(L . J .