SILICA. 
269 
Transparent and beautiful crystals, but which seldom exceed an inch in length, are still 
found in considerable abundance on Diamond island, and at Diamond point, about a mile north 
of the former. They are usually contained in cavities in the calciferous sandstone, and are 
associated with crystals of calcareous spar and pearl spar. Small particles of anthracite are 
also occasionally found in these cavities, as is the case in Herkimer county. Perfect crystals 
Fig. 176. 
Fig. 177. 
r 
Fig. 178. 
Fig. 179. 
Fig. ISO. 
Fig. 181. 
of large size are now very rare at these localities. Figs. 176, 177, 178 and 179 represent some 
forms obtained at Diamond Point. Fig. 180 is from Diamond island. 
Westchester County. Drusy quartz occurs in geodes and cavities in hornstone, which 
almost approaches calcedony, in the vicinity of New-Rochelle. It is associated with serpen¬ 
tine and other magnesian minerals. 
Common quartz is found in masses of some size, in the vicinity of the village of Yonkers, 
and also near West-Farms, where it is of a rose colour. 
At the marble quarry at Hastings, there are veins of calcedony, from \ to \ inch in width, 
between the layers of the rock. The specimens are translucent, pale yellow and white. 
To the above I add, Fig. 
181, the plagiedre of llaiiy, 
which, according to She¬ 
pard, is found on the White 
mountains in New-FIamp- 
shire ; Fig. 182, the emar- 
gine of Haiiy, and Fig. 183 
from Shepard, both of which 
occur at Quebec, Canada. 
Fig. 181. P on x 148° 
42'; r on x 167° 56Q * on 
x 125° IP. 
Fig. 182. P on f or z on 
/141° 40'. 
Fig. 183. P on o 160° 
15'; o on o 125° 10' ( She¬ 
pard ). 
g' 
