Mineralogy of Orange County, JY. Y. 327 



massive Hornblende. Delicate six-sided tables of Grapbite are 

 often found implanted upon the Hornblende crystals, especially 

 where the Hornblende occurs shooting into cavities w^ith Calcareous 

 Spar. The Augite, found in like manner, in loose masses and dis- 

 seminated through the Limestone in place, is not remarkable for its 

 crystals, but for the variety of colors it exhibits. The prevailing 

 hue is an hair brown, often deeply tinged with red. It is either in 

 small rounded grains disseminated through the Limestone, or in en- 

 tire masses, the grains of which are sharply angular. It was called for 

 a time Pyrallolite, and afterwards Hornblende ; but the cleavages it 

 presents leave no doubt concerning its true character. It is in break- 

 ing up masses of this rock, that we sometimes meet with seams of Cal- 

 careous Spar filled with small octahedral Spinels of a black color and 

 a very high degree of lustre. Spinels of a dull, greenish black hue 

 in single crystals, having triangular cavities upon their faces are found 

 loose in the soil. These are often upwards of an inch in diameter, 

 and sometimes hemitropes in form. Brucite is also found here, pos- 

 sessed of a garnet red tinge, diftused through the Limestone along 

 v/ith Mica in small crystals of the same color, and Hable, at first view 

 to be confounded with Bronzite. 



Following the knoll through the wood to the northwest, for the 

 distance of five or six rods from the spot above described, we come 

 to a place where the Limestone crops out, and where the marks of 

 considerable labor appear. The blasting has been confined to one 

 spot of not above ten or twelve feet in length, and of about half this 

 width. Upon one side of the trench, the White Limestone affords 

 Spinel, and upon the other Pargasite and Idocrase. The Spinel is 

 distinguished for the perfection and distinctness of its crystallization. 

 The form of its crystal is the octahedron with equally produced faces. 

 The most frequent color is a dark greenish black, from which it passes 

 through bluish tinge to purplish grey. The crystals are opake, or 

 but slightly translucent. They vary in size from that of a pea to 

 that of a hazle-nut and being thickly interspersed through the snow- 

 white Limestone, which is here in large foliated concretions, and equal- 

 ly penetrated, also, by large grains of wax colored crystals of Brucite, 

 the specimens they form are possessed of unusual beauty and inter- 

 est. Upon the other side of the excavation, the Brucite and Spinel 

 are replaced by Pargasite and Idocrase, the one predominating to the 

 exclusion of the other, and occurring so plentifully as to form the ma- 

 jor part of the rock. This Pargasite has generally been called Cocco- 



