252 DESCRIPTIONS OF MINERALS. 



dirty, need only be thrown into the fire for a few minutes 

 to be white again. The ancients, who were acquainted with 

 its properties, are said to have used it for napkins, on ac- 

 count of the ease with which it was cleaned. It was also 

 the Avick of the lamps in the ancient temples ; and because 

 it maintained a perpetual flame without being consumed, 

 they named it asbestos, unconsumed. It is now used for 

 the^same purpose by the natives of Greenland. The name 

 amianthus alludes to the ease of cleaning it, and it is de- 

 rived from amiantos, undefiled. Asbestus is extensively 

 used for lining iron safes, and for protecting steam pipes 

 and boilers. The best locality for collecting asbestus in the 

 United States is that near the Quarantine, in Eichmond 

 County, X. Y. 



AntlwphyUite is related in the angle of its prisni to hornblende, but 

 is trimetric. In composition and its infusibility before the blowpipe, 

 it is near bronzite. B. B. it becomes magnetic. From Kongsberg in 

 Norway, and near Modum. Kupfferite bas tbe bornblende angle, but 

 in composition it is like enstatite, being a magnesium silicate. 



Arfoedsonite. Xear bornblende ; but contains over 10 per cent, 

 of soda, like acmite. 



Crocidolite. Xear arfvedsonite in composition. A lavender-blue or 

 leek-green fibrous mineral from Orange River. Soutb Africa, and from 

 tbe Yosges ; also from Rbode Island (A. H. Cbester). 



Gastadite. A dark blue to azure-blue mineral related to ampbibole, 

 from tbe valleys of Aosta and Locano. 



Glaucophane. A bluisb mineral witb tbe ampbibole angle, from tbe 

 Island of Syra. Wield (site may be tbe same mineral. 



MUarite. Trimetric, of tbe composition (KHjCa^Al 03081, Q ; tbe 

 quantivalent ratio for bases and silica 1:4; being tberefore a quater- 

 silicate instead of a bisilicate. 



BeryL — Emerald. 



Hexagonal. In hexagonal prisms, usually without regular 

 terminations. Cleavage basal, not very distinct. 

 Rarely massive. 



Color green, passing into blue and yellow ; 

 color rather pale, excepting the deep and rich 

 green of the emerald. Streak uncolored. Lus- 

 tre vitreous : sometimes resinous. Transparent 

 to subtranslucent. Brittle. H. = 7*5-8. G-. = 

 2-65-2-75. 

 Varieties. The emerald is the rich green variety : it owes 

 its color to the presence of chromium. Beryl includes the 

 paler varieties, which are colored by oxide of iron. Aquat 



