Miscellaneous Localities of Minerals, 57 



is fine grained, with but little mica, except in some veins, 

 which seem almost cooipletely formed of it — feldspar white, 

 quartz limpid, with a bluish tint. Part of the granite re- 

 tains its original colours, but the greater part is deeply stain- 

 ed brown and yellow, with oxide of iron. Some points of 

 it are of a beautiful pink colour, as if stained with manga- 

 nese. The minuter fragments consist of the quartz and 

 J felspar, covered with delicate incrustations of mmute crys- 

 tals of sulphur, having the appearance of sublimated sul- 

 phur. The sulphur is sometimes pale yellow, but has most- 

 ly a greenish tinge — much of the sulphur came to hand in 

 the state of powder full of crystals of iron pyrites, from the 

 size of a pea down to the minutest grains. The explana- 

 tion of this appearance seems easy — the centre of the gran- 

 ite probably formed a geode, lined or filled with pyrites. 

 By a spontaneous decomposition, attended with the extri- 

 cation of heat, the sulphur was sublimated, and the iron 

 converted into oxide has stained the stone. 



This apparently unimportant fact may have no little 

 weight in settling the question of the origin of volcanoes. 

 It may have been only on a very small scale, what -SItna 

 is in the large way. J. G. P. 



Localities of Minerals near West-Point, from Dr. Cutbush. 



Sulpliuret of Molybdenum, in granite and gneiss, West- 

 Point, and Constitution Island, opposite the Point. 



Kaolin, from decomposed feldspar, accompanying quartz. 

 West-Point. 



Tremolite, glassy and fibrous, or asbestifurm, in sienite. 

 West-Point. 



Schorl in granite. West-Point. 



Adularia in granite rock. West-Point. 



Coccolite, Fort Putnam, West-Point, in blocks. This 

 mineral I observed nearly two years since. 



Garnets, common in gneiss, and imbedded in mica slate. 

 West-Point. 



Precious Serpentine, Putnam County. This is remarka- 

 bly elegant. The locality was first observed by Captain 

 Douglass. 



Glassy Actynolite. Vicinity of West-Point. 



Ma'/nef^r i: on ore. Constitution Island. 



Vol. VII.— ]\o. 1. 8 



