SUBSILICATES. 281 



tolite, euclase, and part of staurolite, hydrogen, that is, the 

 hydrogen of the water found on analysis. In chondrodite, 

 topaz, and some tourmaline, fluorine replaces part of the 

 oxygen. 



Chondrocyte. — Humite in part (Scacchi's Type II). 



Monoclinic. Cleavage indistinct. Usually in imbedded 

 grains or masses. Color light yellow to brownish yellow, yel- 

 lowish red, and garnet-red. Lustre vitreous, inclining a little 

 to resinous. Streak white, or slightly yellowish or grayish. 

 Translucent or sub translucent. Fracture uneven. H. = 6- 

 6-5. G.=3-l-3-25. 



Composition. Mg s 14 Si 3 ; but a portion of the magnesium 

 replaced by iron, and a part of the oxygen by fluorine. A 

 specimen from Brewster's, New York, afforded Silica 34*1, 

 magnesia 53*7, iron protoxide 7*3, fluorine 4*2, with 0*48 of 

 alumina =99*72. 



B.B. infusible. Decomposed by hydrochloric acid ; the 

 solution gelatinizes on evaporation. 



Biff, As it occurs only in limestone it will hardly be con- 

 founded with any species resembling it in color when the 

 gangue is present. It does not fuse like tourmaline or gar- 

 net, some brownish-yellow varieties of which it approaches 

 in appearance. The name is from the Greek chondros, a 

 grain. 



Obs. It is abundant in the adjoining counties, Sussex, 1ST. J., 

 and Orange, N. Y., occurring at Sparta and Bryam, N. J., 

 and in Warwick and other places in N. Y. ; at the Tilly 

 Foster Iron Mine, Brewster's, Putnam County, N. Y., it is 

 very abundant. At Vesuvius it occurs in small crystals. 



The species was early named Chondrodite, from Finland 

 specimens ; soon afterward small crystals, found in the lavas 

 of Somma (Vesuvius), were named Humite, and both were 

 referred to the same species. It has recently been ascer- 

 tained that under this species, two species of different an- 

 gles and form, but related composition and physical charac- 

 ter, are included. For these species the names Humite and 

 Clinohumite have been adopted. 



Humite is orthorhombic, and embraces part of the Humite 

 crystals of Vesuvius (Scacchi's Type I.), and some large 

 coarse chondrodite-like crystals found at Brewster's, N. Y. 



Clinohumite is monoclinic, and includes Scacchi's Type III. 



