APATITE 531 



suggested under agate, that the material was some mineral other than fluor-spar. Pale 

 yellow and rose-red beads cut out of fluor-spar have been found, together with beads of 

 sodalite, in the ancient ruins of Tiahuanaco, near Lake Titicaca, on the high Bolivian 

 plateau. 



APATITE. 



Apatite is another mineral which occurs of various colours closely resembling those of 

 certain precious stones, and for this reason transparent stones are sometimes cut. Apatite is 

 better suited than fluor-spar for this purpose, since it has a hardness of 5 and it possesses no 

 distinct cleavage. Chemically it is a phosphate of calcium containing chlorine and fluorine ; it 

 crystallises in the hexagonal system, the crystals, which are often very beautiful, usually 

 taking the form of a six-sided prism with a basal plane perpendicular to the prism-faces, or 

 with other terminal faces. 



In a pure condition apatite is perfectly colourless and limpid, but by the intermixture 

 of foreign substances it becomes variously coloured. Lilac, violet, or pale green crystals of 

 apatite are found with the tin ores of the Erzgebirge, for example, at Ehrenfriedersdorf in 

 Saxony, and in the old copper mine of Kirabinsk, near Miask, in the Urals. Pale yellow apatite 

 the so-called asparagus-stone, occurs in talc-schist in the Tyrolese Alps. The deep green 

 variety, known as moroxite, occurs embedded in crystalline silicate-rocks and in marble at 

 many places ; for example, in North America, especially in Canada ; on the Sludianka, a 

 river flowing into Lake Baikal, in Siberia ; at Arendal, in Norway. Sky-blue crystals are 

 found at certain localities in Australia and Ceylon. Certain green, rose-red, and violet 

 apatites, remarkable for their transparency and the beauty of their colouring, occur with 

 tourmaline in the crevices of the granite of Mount Apatite, near Auburn, in Androscoggin 

 County, in the State of Maine, U.S.A., and were formerly mistaken for tourmaline. 



The variously coloured apatites just described, when sufficiently transparent, which is 

 not usually the case, may be cut as gems. The variety most frequently cut, perhaps, is 

 the green moroxite from Canada, but even this is used to only a very limited extent and is 

 very low in price. 



The mineral may be distinguished from other similarly coloured stones by its hardness 

 and its specific gravity, the latter feature approaching very closely to the specific gravity 

 of fluor-spar, which is 3"2. Apatite is doubly refracting and slightly dichroic, characters 

 which serve to disbinguish it from fluor-spar. From beryl and emerald, to which some 

 cut apatites are very similar in appearance, the mineral may be distinguished, as pointed out 

 above, by its hardness and its specific gravity, apatite sinking in test liquid No. 3 

 (sp. gr. = 3'0), in which beryl and emerald float. 



