LAZULITE— CALLAINITE 403 



LAZULITE. 



There is, perhaps, but one mineral which, by any possibility, could be mistaken for 

 turquoise, and which may sometimes be substituted for this stone. The mineral lazulite 

 (not to be confused with lapis-lazuli, which will be considered below) probably never finds 

 application as a gem under this name. It occurs in nature as monoclinic crystals of a 

 sky-blue colour, and also in compact finely granular masses known as blue-spar. In 

 chemical composition it is very similar to turquoise, being a hydrous aluminium phosphate, 

 but containing in addition some magnesium and iron. Its hardness is rather less than that 

 of turquoise, being 5^ ; the specific gravity, 3'1, is considerably higher, so that lazulite 

 sinks in liquid No. 3 (sp. gr. = 3"0). The lustre is of the common vitreous type, showing 

 no inclination to waxiness, so that in this respect also lazulite diflfers from turquoise. Fine 

 crystals of lazulite are found in a friable sandstone at Graves Mountain, Lincoln County, 

 Georgia, U.S.A. ; also on quartz which, in the form of thin veins, penetrates clay-slates at 

 Werfen in Salzburg, where the massive blue-spar occurs. Massive material of a fine deep 

 blue colour is also found in Brazil. Lazulite as a precious stone is met with extremely 

 rarely in the trade. 



CALLAINITE. 



Callainite, or callais, is a mineral which was used as a precious stone in prehistoric 

 times. It is found exclusively in an ancient Celtic grave at Mane-er-H'rock, near Lock- 

 mar iaquer, in Brittany, as rounded fragments ranging in size from that of a flax-seed to that 

 of a pigeon's egg. In many respects it resembles turquoise, but differs from this stone in 

 being beautifully translucent. It is almost always green in colour, the shades ranging from 

 apple-green to emerald-green ; it is sometimes veined and spotted with white, blue, black, or 

 brown. In chemical composition callainite is very similar to turquoise, being a hydrous 

 phosphate of alumina ; the constituents, however, are present in rather different proportions 

 in the two stones. Like turquoise, this mineral is not distinctly crystallised, being an 

 aggregate of microscopically small grains. The hardness ranges from 3J to 4, and the 

 specific gravity from 2"50 to 2"52. Callainite was obviously used by the ancient Celts as an 

 ornamental stone, but where the specimens found in these ancient graves were originally 

 brought from has not yet been discovered. The mineral is probably a variety of variscite, 

 but is more transparent and of a finer colour than typical specimens of this mineral. 



