Chemical Examination of American Minerals. 67 



It constitutes a compact stone, through which a few scales 

 of mica are interspersed, and having somewhat the appear- 

 ance of clay-stone, though less compact and much softer. 

 Color light grayish-blue. Powder light blue. 

 It is harder than gypswm, but soft enough to be scratched 

 by the nail. Sectile. 



The panicles when scraped off with a knife, feel gritty be- 

 tween the teeth. 



Specific gravity 2'606. 



It does not fuse per se before the blow-pipe. 



The constituents obtained by analyzing it were as follows. 



Silica, 55620 



Alumina, 17-208 



Soda, 12-160 



Peroxide of iron, _ _ _ , 7*612 



Lime, - 2-256 



Magnesia, 0-112 



Water, ------ 4-600 



99-568 



It consists of four bisilicates, namely, 

 Bisilicate of alumina, 

 Bisilicate of soda, 

 Bisilicate of iron, 

 Bisilicate of lime. 



Were we to consider the bisilicates of iron and lime as only 

 accidentally present, pipe-stone would be a compound of, 



1 atom bisilicate of soda, 



2 atoms bisilicate of alumina. 



Differing from analcime and chabasie, by the absence of 

 water, and by an atom less of bisilicate of alumina. But 

 whether this stone be a chemical compound, or only a mixture, 

 must remain doubtful at present. 



