CHLORITE GROUP. 319 
Composition. A specimen from Chester Co. , Pennsylvania, 
afforded Silica 31°34, alumina 17: Ads chromium sesquioxide 
1°69, iron sesquioxide 3°85, magnesia 33°44, water 12°60= 
10039. B.B. and with acids nearly hke penninite. A va- 
riety from Willimantic, Ct., exfohates hike vermiculite and 
jefferisite. : : 
Kotschubeite is a red variety from the Urals. 
Clinochlore and Grastite are here included. Occurs at 
Achmatovsk and elsewhere in the Urals ; at Ala, Piedmont ; 
at Zermatt ; at Westchester, Unionville ‘and Texas, Pass 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 hght. Lamine 
not elastic. 
Composition. A specimen from St. Gothard afforded Sili- 
ca 20°36, alumina 18°56, iron protoxide 28°79, magnesia 
LO9, water 8-96—98° 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, Ogeotte, Helmtnthe belong here. Cccur at St. 
Gothard, at Greiner in the Tyrol, at Traversella in Pied- 
mont, and many other places in Europe. Also at Steele’s 
Mine, N. C. 
Leuchtenbergite is a prochlorite with the base almost solely magne- 
sium. 
Aphrosiderite, Metachloritc are near the above in composition. 
Venerite is a pate-green earthy chlorite, from a magnetite mine in 
Berks County, Pa. 
Corundophiiite 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.= 
5°30. Consists mainly of silica, iron oxides, and water, with a little 
manganese oxide. From Bohemia and Cornwall. 
Thuringite. Another hydrous iron silicate, having G.—83:15-3°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. amine rather brittle. 
Color white, grayish, reddish. Lustre ofecleavage surface 
