268 DESCRIPTIONS OF MINERALS. 
A green variety occurs at Unity, Maine, near Baltimore, 
Md., and at Chestnut Hill, Pa. Prismatic mica is found at 
Russel, Mass. | 
On account of the toughness, transparency, and the thin- 
ness of its folia, mica was formerly used in Siberia for glass in 
windows, whence it has been called Muscovy glass. It is in 
common use for lanterns, and also for the doors of stoves, 
and other purposes which demand a transparent substance 
not atiected by heat. 
Lepidolite, or Lithia mica. Resembles muscovite. Color rose-red, 
and lilac to white ; in crystalline plates and aggregations of scales. 
It contains from 2 to 5 per cent. of lithia, and hence B.B. imparts a 
deep crimson color to the flame. 
From Rozena in Moravia; Zinnwald in Bohemia (the Zinnwaldite) ; 
Saxony ; the Ural; Sweden; Cornwall; Paris, and Hebron, Maine ; 
Chesterfield, Mass.; Middletown, Conn. The red mica of Goshen is 
muscovite. 
Cryophyllite has the same constituents as lepidolite. It fuses easily 
in the flame of a candle. From Cape Ann, Mass. 
SCAPOLITH GROUP. 
The Scapolite species are dimetric in crystallization, 
usually white in color or of some light shade, and analyses 
afford alumina and lime with or without soda. The lime 
scapolites are unisilicate in ratio; the others, containing 
alkali, have, with one exception, more silica than this ratio 
requires. 
Wernerite— Scapolite 
Dimetric. 1: 1=136° 7’. Cleavage rather indistinct paral- 
lel with ¢-¢ and J. Also massive, sub- 
lamellar, or sometimes faintly fibrous 
in appearance. 
Colors light; white, gray, pale blue, 
greenish or reddish. Streak uncolored. 
Transparent to nearly opaque. Lustre 
usually a little pearly. H.=5-6. G.= 
2°6-2'8. 
Composition. (4(Ca, Nay)2Al),0151;= 
Silica 48:4, alumina 28°5, lime 1871, 
soda 5:0=100. B.B. fuses easily with intumescence to a 
white glass. Imperfectly decomposed by hydrochloric acid. 

