532 
GEOLOGY OF THE FIRST DISTRICT. 
point from which Arnold escaped. The augite here forms a heavy bed in gneiss rock asso¬ 
ciated with limestone. The augite is crystalline, grey, and contains scales and hexagonal 
plates of plumbago. A vein of a mineral that I suppose to be the pyrophyllite, traverses the 
augite rock. The mineral from this locality has the aspect of silvery mica, which can be 
dug out of the vein in masses so as to give plates of two or three inches in diameter, in 
rhombic and hexagonal crystals like mica ; but the plates have not so much elasticity as mica, 
nor so much unctuosity as talc. The plates of this mineral, when heated, exfoliate, and 
spread out like the vermiculite of Rhode-Island, so that a plate of an eighth of an inch thick 
before being heated, becomes one-half to one and a half inches thick in the fire, the laminae 
all separating, but remaining still attached to each other. 
Another interesting locality of augite rock is on Anthony’s Nose mountain, at the “ White 
mine.” It is here associated with a bed of brown spar, containing magnetic oxide of iron 
and plumbago. An ore of cerium is supposed to have been observed at this place. 
Rocks of augite containing scapolite and sphene, were seen in many places on the shore of 
the Hudson at the southern base of Anthony’s Nose mountain, but the localities from which 
they had fallen in the cliffs above were not traced out. 
Augite containing sphene, scapolite, and associated with verd antique, diallage and horn¬ 
blende, occurs at the base of the cliffs of Bull hill, near the shore of the Hudson ; but the 
beds from which they had fallen, although some explorations were made, were not seen. The 
augite occurs under various forms, as green, yellowish, grey, crystalline, crystallized granu¬ 
lar (coccolite of white, green, grey, yellowish and red), fibrous, and in acicular crystals. 
Augite also occurs at Hustis’s quarry in Phillipstown, as augite, white and green coccolite, 
diopside and sahlite. 
Coldspring was an interesting locality of augite rock some years ago, but a block of buildings 
has been raised over the locality where so many beautiful specimens were procured. The 
augite rock is there associated with gneiss and granite, and contains scapolite and sphene in 
abundance. The largest and most beautiful crystals of sphene I have ever seen were obtained 
at this place by Dr. Barratt in 1822, now of Middletown, Connecticut. Augite is so common 
a rock in Putnam county, that it is unnecessary to multiply localities. 
In Westchester county, it was seen more rarely. It has been mentioned as occurring at 
the Kingsbridge marble quarries, but it is not abundant. It was observed in the limestone in 
Mount-Pleasant, near the granitic rocks in the vicinity of the copper mine adit at Sparta, and 
in the cliff on the shore one hundred or two hundred yards south of Sparta, where the transverse 
heave has shifted the dip of the rocks. 
, 6. Greenstone. 
This rock traverses the strata in many places in Putnam and Westchester counties. In 
some places it has the aspect of compact trap, like basalt, but more frequently the hornblende 
predominates and gives its characters to the rock. It traverses, and is intertruded in sheets 
and irregular masses among the gneiss and other rocks in the same way as granite and sienite; 
