304 DESCRIPTIONS OF MINERALS. 
veins; in large crystallizations at Berufiord, Iceland ; 
and Vendayah Mts., Hindostan ; also at Isle Skye; near 
Glasgow ; Fassa Valley ; at Bergen Hill, N. J., im trap ; at 
Hadlyme, Conn., and Chester, Massachusetts, on gneiss ; 
near Baltimore, on a syenitic schist (Beaumontite) ; at 
Peter’s Point and Cape Blomidon, and other places in 
Nova Scotia, in trap. 
The species was named by Brooke after Mr. Heuland, 
of London. 
Brewstcrite. Crystals monoclinic with a perfect pearly cleavage 
like heulandite ; but M:T=93' 40. H.=4}-5. G.=2-45. The for- 
mula is analogous to that of heulandite, but baryta and strontia take 
the place of the lime and soda. 
Hpistilbitc. Composition like that of beulandite, but occurs in short 
and very obtuse rhombic prisms, (7A 7=135" 10’), at Skye ; the Faroe 
Ids., in Iceland ; at Margaretville, in Nova Scotia. 
Mordenite. Fibrous mineral from Morden, Nova Scotia. 
Pilinite. Jn slender needles, from Silesia. 
Foresite. Near stilbite. From Elba. 
Ill]. MARGAROPHYLLITE SECTION. 
Talc. 
Trimetric. In right rhombic or hexagonal prisms. JAZ 
=120°. Usually in pearly foliated masses, separating easily 
into thin translucent foha. Sometimes stellate, or diver- 
gent, consisting of radiating lamine. 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°5-2°8. Lam- 
ine flexible, but not elastic. 
There are the following varieties : 
Foliated Taic. he pure foliated talc, of a white or 
ereenish-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 varicty, with a 
pearly lustre. Potstone or Lapis Ollaris is impure soap- 
stone of grayish-green and dark-green colors, and slaty 
structure. 7 


