CHLORITE GROCP. 319 



Composition. A specimen from Chester Co., Pennsylvania, 

 afforded Silica 31*34, alumina 17*47, chromium sesqnioxide 

 1-69, iron sesqnioxide 3*85, magnesia 33*44, water 12*60 = 

 100*39. B.B. and with acids nearly like penninite. A va- 

 riety from Willimantic, Ct., exfoliates like vermicnlite and 

 jefferisite. 



Kotsclmieite is a red variety from the Urals. 



ClinocTdore and Grastite are here included. Occurs at 

 Achmatovsk and elsewhere in the Urals ; at Ala, Piedmont ; 

 at Zermatt ; at Westchester, Union ville and Texas, Pa. ; at 

 Brewster's, N. Y. 



Prochlorite. — Chlorite in part. 



Hexagonal. Similar in cleavage and mica-like characters 

 to the preceding. Color green to blackish-green ; some- 

 times red across the axis by transmitted, light. Laminae 

 not elastic. 



Composition. A specimen from St. Gothard afforded Sili- 

 ca 25*36, alumina 18*56, iron protoxide 28*79, magnesia 

 17*09, water 8*96=9S # 70 ; and a North Carolina specimen, 

 Silica 24*90, alumina 21*77, iron sesquioxide 4*60, iron 

 protoxide 24*21, manganese protoxide 1*15, magnesia 12*78, 

 water 10*59 = 100. B.B. same as for preceding. 



Lophoite, Ogcoitc, Helminthe belong here. Occur at St. 

 Gothard, at Greiner in the Tyrol, at Traversella in Pied- 

 mont, and many other places in Europe. Also at Steele's 

 Mine, X. C. 



Leuchteribergite is a prochlorite with, the base almost solely magne- 

 sium. 



Aphrosiderite , MetacMorite are near the above in composition. 



Venerite is a pale-green earthy chlorite, from a magnetite mine in 

 Berks County, Pa. 



Corundophilite is a chlorite near prochlorite in composition. Occurs 

 with corundum at Asheville, N. C. 



Grochauite is from Grochau in Silesia. 



Cronstedtite. Hexagonal, with perfect basal cleavage. Black. G. = 

 3*35. Consists mainly of silica, iron oxides, and water, with a little 

 manganese oxide. From Bohemia and Cornwall. 



Thuringite. Another hydrous iron silicate, having Gh =315-3*20, 

 from Thuringia, and also Hot Springs, Arkansas, and near Harper's 

 Ferry, on the Potomac. Pattersonite, from Unionville, Pa., is near it. 



Margarite. — Emerylite. Diphanite. Clingmanite. Corundellite. 



Trimetric. Foliated, mica-like. Laminae rather brittle. 

 Color white, grayish, reddish. Lustre of cleavage surface 



