304 DESCKIPTIONS OF MINERALS. 



veins ; in large crystallizations at Bernnord. Iceland ; 

 and Yendayah Mts., Hindostan ; also at Isle Skye ; near 

 Glasgow ; Fassa Valley ■ at Bergen Hill. X. J., in trap ; at 

 Hadljme, Conn., and Chester, Massachusetts, on gneiss ; 

 near Baltimore, on a syenitic schist {Beaumontite) ; at 

 Peters Point and Cape Blomidon, and other places in 

 Nova Scotia, in trap. 



The species was named by Brooke after Mr. Henland, 

 of London. 



Brewsterite. Crystals monoclinic with a perfect pearlv cleavage 

 like heulandite ; but M : T=93° 40'. H.=-U-o. G.=2 45." The for- 

 mula is analogous to that of heulandite, but baryta and strontia take 

 the place of the lime and soda. 



Epistilhitc. Composition like that of heulandite, but occurs in short 

 and very obtuse rhombic prisms, {I/\I=1%5° 10), at Skye ; the Faroe 

 Ids. , in Iceland ; at Margaretville, in Nova Scotia. 



Mbrdenite. Fibrous mineral from Morden, Nova Scotia. 



Pilinite. In slender needles, from Silesia. 



Foresite. Near stilbite. From Elba. 



III. MARGAEOPHYLLITE SECTION. 

 Talc. 



Trimetric. In right rhombic or hexagonal prisms. I/\l 

 = 120°. Usually in pearly foliated masses, separating easily 

 into thin translucent folia. Sometimes stellate, or diver- 

 gent, consisting of radiating laminae. Often' massive, con- 

 sisting of minute pearly scales ; also crystalline granular, or 

 of a fine impalpable texture. 



Lustre eminently pearly, and feel unctuous. Color some 

 shade of light green or greenish white ; occasionally silvery 

 white; also grayish green and dark olive-green. H. = 1- 

 1*5; easily impressed with the nail. G. =2'o-2S. Lam- 

 inae flexible, but not elastic. 



There are the following varieties : 



Foliated Talc. The pure foliated talc, of a white or 

 greenish-white color. 



Soapstone or Steatite. Gray or grayish green, and either 

 massive, crystalline granular, or impalpable : very greasy to 

 the touch. French "chalk is a milk-white variety, with a 

 pearly lustre. Potstone or Lapis Ollaris is impure soap- 

 stone of grayish-green and dark-green colors, and slatv 

 structure. " 



