PRIMARY ROCKS, 
533 
and many of the masses classed with this rock would be classed with sienite, but for the 
fineness of the grain, being of about the texture of a sandstone, composed of black hornblende 
with grains of white and grey felspar. 
Well characterized dykes of greenstone of the basaltic kind were seen in a few places in 
Putnam county. One was near the mills northeast of Hustis’s quarry; and another near the 
road from Coldspring to Davenport’s corners, about two and a half miles from the former 
place. 
The speckled greenstone in which hornblende prevails, may be seen abundantly in almost 
every part of the Highlands of Putnam and Orange counties. 
Hornblendic Rocks. 
This is a convenient repository for those rocks that are not so perfectly characterized as to 
be included under the preceding heads, Hornblendic rocks form a very considerable propor¬ 
tion of the mass of the Highlands in Putnam, and in fact in Rockland and Orange counties ; 
but those parts composed of sienite, hornblendic gneiss, hornblende slate, and greenstone, 
have been described. Perhaps the remainder classed under this head might properly have 
been described as greenstone, for they have the geological relations of that rock, being evi¬ 
dently in many instances an intrusive rock ; but very frequently it is almost pure hornblende, 
and could not, in conformity with the generally received composition of greenstone, be 
described as such. 
Hornblendic rocks of this character occur near the “ marble quarry ” where such a variety 
of magnesian minerals occur associated with serpentine, near New-Rochelle, in Westchester 
county. Manganesian garnet also occurs in the hornblende, which is strongly crystalline and 
resplendent. 
It has been mentioned as common on the shore of the Hudson between Peekskill and 
Yonkers, while tracing the connections of the white metamorphic limestones. It is particu¬ 
larly well characterized about one mile east and southeast of Verplanck’s point, where the 
hornblende is strongly crystalline and resplendent. This rock extends some miles to the 
north-northeast, and forms very considerable masses. It is often interlaminated with the 
gneiss.* 
At Verplanck’s point, it forms veins, strings, and interlaminated masses among the lime¬ 
stone, and is an instructive locality. 
Hornblende rock is abundant in Anthony’s Nose mountain, between Anthony’s Nose and 
Roya hook. Hornblende forms a constituent of a large share of the rocks of this mountain. 
Hornblende is also common between Anthony’s Nose and Sugarloaf mountains. 
Greenstone, hornblendic gneiss, and hornblende rock occur at the northern base of the hill 
* This hornblendic rock assumes in the same mass the characters of sienite, “ primitive greenstone,” hornblende rock, hom- 
blendic gneiss, and hornblende slate. It is sometimes distinctly stratified, sometimes perfectly granitic in its texture, and is 
composed of a dark brownish felspar, black hornblende, and black mica. They all seem contemporaneous. 
