296 DESCRIPTIONS OF MINERALS. 



pinny, and the Salisbury Crag, near Edinburgh, are some 

 of the foreign localities. 



Prehnite receives a handsome polish and is sometimes 

 used, for inlaid work. In China it is polished for orna- 

 ments, and large slabs have been cut from masses brought 

 from there. 



Cldorastrolite and Zo/wchlorite, from the Lake Superior region, are 

 impure prelmite. 



ChalcomorpMte. A hydrous calcium silicate, from calcite in cavities 

 of lava, containing but 25 '4 per cent, of silica. 



Gii-mondite (Ztagonite). A hydrous lime-aluminum silicate, occur- 

 ring in trimetric crystals resembling square octahedrons ; found in 

 lava at Capo di Bove, near Rome. 



Edingtonite. A hydrous barium-aluminum silicate. Occurring in 

 crystals and massive. From the Kilpatrick Hills, with harmotome. 



Carpholite. A manganese- aluminum silicate, occurring in silky, 

 yellow, radiated tufts. From the tin mines of Schlackenwald. 



Pyrosmalite. A manganese-iron silicate and chloride, from Sweden. 



Calamine. A hydrous zinc unisilicate. See p. 157. 



Villarsite. Probably altered chrysolite. 



Cerite, Tritomite, Erdmannite, are cerium and lanthanum silicates. 



Thorite {Orangite) and Eucrazite, are thorium silicates ; the latter 

 hydrous. 



Allophane. 



In amorphous incrustations, with a smooth small-mam- 

 millary surface, and often hyalite-like, and sometimes pul- 

 verulent. Color pale bluish-white to greenish-white, and 

 deep green ; also brown, yellow, colorless. Translucent. 

 H.=3. G.=l-85-l-89. 



Composition. Mostly Al 3 Si -I- 6 (or 5) aq. Silica 23-75, 

 alumina 40*6^, water 35*63 = 100. In the closed tube yields 

 much water. B.B. infusible, but crumbles. A blue "color 

 with cobalt solution, and a jelly with hydrochloric acid. 



Occurs in Saxony ; at the Chessy Copper Mine near 

 Lyons ; at a copper mine in Bohemia ; with limonite in 

 Moravia : in Old Chalk Pits near Woolwich, England : witli 

 gibbsite in limonite beds in Richmond, Mass. ; at the cop- 

 per mine of Bristol, Conn.; at Morgantown, Pa. ; copper 

 mines of Polk County, Tenn. 



Colh/rite. A hydrous aluminum silicate containing only 14 to 15 per 

 cent, of silica, and 35 to 40 of water ; and Sclrrotterite is another with 

 11 to 12 per cent, of silica. The latter has been reported as occurring, 

 as a gum-like incrustation, at the falls of Little River, on Sand Moun- 

 tain, Cherokee County, Alabama. Scarbroite is a related mineral 

 of doubtful nature. 



