Mineralogy of Orange County, N. Y. 327 
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massive Hornblende. Delicate six-sided tables of Graphite are 
dien found implanted upon the Hornblende crystals, especially 
where the Hornblende occurs shooting into cavities with Caleareous 
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- 
lire masses, the grains of which are sharply angular. It was called for - 
atime 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 
‘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, diffused through the Limestone along 
with Mica in small crystals of the same color, and liable, at first view 
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 
a place where the Limestone crops out, and where the marks of 
“onsiderable labor appear. The blasting has been confined to one 
‘Potof 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. 
€ form of its crystal is the octahedron with equally produced faces. 
“most frequent color is a dark greenish black, from which it passes 
through bluish tinge to purplish grey. The crystals are opake, or 
but ‘lightly translucent. They vary in size from that of a pea to 
— Mtof 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, 
Specimens they form are possessed of unusual beauty and inter- 
pon the other side of the excavation, the Brucite and Spinel 
" replaced by Pargasite and Idocrase, the one predominating to the 
“clusion of the other, and occurring so plentifully as to form the ma- 
Part of the rock, This Pargasite has generally been called Cocco- 
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