BISILICATES. 251 
Pargasite. Dark-green crystals, short and stout (resem- 
bling fig. 4), with bright lustre, of which Pargas in Finland 
is a noted locality. G.=3-11. 
Composition. Silica 45°5, alumina 14:9, iron protoxide 
8:8, manganese protoxide 1°5, magnesia 14°4, lime 14:9= 
100. 
Hornbiende. Black and greenish-black crystals and mas- 
sive ieemens: Often in slender crystallizations like actino- 
lite ; also short and stout hke figs. “4 and 5, the latter more 
especially. It contains a large percentage of iron oxide, and 
to this owes its dark color. It is a tough minere!, as is im- 
plied in the name it bears. This character, however, is best 
seen in the massive specimens. Parg: asite and hornblende 
contain both alumina and iron. 
Composition of a hornblende: Silica 48-8, alumina 75, 
magnesia 13°6, lime 10°2, iron protoxide 18 8, manganese 
protoxide 1:1=100. 
Obs. Hornblende is an essential constituent of certain 
rocks, as syenyte, dioryte and hornblende schist. Actino- 
lite is usually found in magnesian rocks, as talc, steatite or 
serpentine; tremolite in granular limestone and dolomite ; 
asbestus in the above rocks and also in serpentine. Black 
erystals of hornblende occur at Franconia, N. H., Chester, 
Mass., Thomastown, Me., Willsboro’, N. Y., in Orange 
County, N. Y., and ‘elsewhere. Pargasite occurs at Phipps- 
burg and Parsonsfield, Me.; glassy actinolite, in steatite 
or tale, at Windham, Readsboro’, and New Fane, Vt., 
Middlefield and Blandford, Mass.; and radiated varieties 
at the same localities and many others. ‘Tremolite and 
gray hornblende occur at Canaan, Ct., Lee, Newburgh, 
Mass., in Thomaston and Raymond, Me., Dover, Kings- 
bridge, and in St. Lawrence County, ING NE seat Chestnut 
Hill, Penn. ; at the Bare Hills, Md. Asbestus at many of 
the above localities : ; also Brighton and Sheffield, Mass. 3 
Cotton Rock and Hustis’s farm, Phillipstown, N. Y., near 
the Quarantine, Richmond County, N.Y. Mountain lea- 
ther is met with at Brunswick, N.J. Hdenite, a white 
aluminous kind, oceurs at. Edenville, N. Y. 
Asbestus is the only variety of thris species of any use in 
the arts. The flax-like variety is sometimes woven into 
fire-proof textures. Its incombustibility and slow conduc- 
tion of heat render it a complete protection against the 
flames. It is often made into gloves. A fabric when 

