SILICA. 
295 
Fig. 217. 
Fig. 218. 
M 
Fl s- 219 - strewed over with loose fragments 
of crystals. They are usually of 
the form represented in Fig. 217, 
which is th eperihexaedre of Hauy> 
with the face r much extended, and 
the other faces very narrow, so as 
to give the crystal the appearance 
of a flattened table. 
Near Knapp’s quarry, twin crys¬ 
tals of white pyroxene have been obtained, the composition of which will be understood from 
an inspection of Figs. 218 and 219. They closely resemble the compound crystals of albite. 
Rockland County. At the Horsenclever iron mine, in the town of Haverstraw, fine spe¬ 
cimens of the lamellar variety are found, which closely resemble hypersthene. 
St. Lawrence County. About a mile southwest of the village of Gouverneur, there is 
a locality of crystallized pyroxene of a light grey colour. The forms are the primary, and an 
eight-sided prism, but they are usually without terminations. They are associated with crys¬ 
tallized hornblende and dark green coccolite, and occur in white limestone. 
In the town of Rossie, two miles north of the village of Oxbow, crystallized pyroxene 
occurs in an aggregate of feldspar, apatite, crystallized hornblende and sphene. It is of a 
green and greyish green colour. Large crystals have been obtained at this locality. They 
are usually of the primary form (Fig. 192), and the modifications Figs. 207 and 208. 
Fig. 220. 
Fig. 221. 
Near iJe Long’s mill, in the town of Hammond, crystal¬ 
lized pyroxene of a dark colour occurs along with zircon, 
feldspar and apatite. The forms are six and eight-sided 
prisms with four terminal planes, represented in Figs. 220 
and 221. M on x 134° 17 / ; ion* 114° 26 / ; x on x 131° 
8k 
Lamellar pyroxene, of a white and greyish white colour, 
is found in abundance near the village of Richville in the 
town of De Kalb. It cleaves like most of the varieties, but 
it is often softer than is usual with this mineral. I attribute 
this to its mixture with serpentine, and it probably belongs to that variety which I call steati- 
tic pyroxene , to be presently noticed. It is associated with tremolite and brown tourmaline, 
the whole contained in white limestone. 
Washington County. In the town of Putnam, on the bank of Lake George, about two 
miles south of Ticonderoga, there are beautiful specimens of lamellar pyroxene. The colour 
varies from grey to nearly black, and some specimens have a high pearly lustre on the faces 
of cleavage, while others have a metallic lustre. It is both foliated and lamellar; and the 
folia, which are sometimes waved or bent, may be obtained of the size of the hand. The 
latter variety is apparently less hard than is usual with this mineral, but this is probably owing 
to its structure. 
/ 
