SILICA. 
261 
Also the forms represented in Figures 134, 135, 136, 137, 138, and the twins 139 and 140. 
These crystals are usually small. 
Fig. 134. Fig. 135. 
Fig. 136. 
Fig. 137. 
Fig. 138. 
Similar crystals are obtained in the slate near the paper mill, two miles west of Catskill; 
and during the process of excavations that were made for the railroad, large and beautiful 
crystals were sometimes thrown out. 
Herkimer County. Uncommonly beautiful specimens of rock crystal, perfectly transpa¬ 
rent, have been found in various parts of this county, especially at Middleville, Fairfield, 
Little-Falls, Salisbury and Newport. They are found sometimes in cavities in the calciferous 
sandstone ; and at others, they lie loosely in the sand, probably produced by the disintegration 
of the rock. Mr. Yanuxem has remarked, that there is probably no locality in the world 
which produces more perfect or more beautiful quartz crystals than Middleville ; and with an 
equal refractive power, they would rival the diamond. They are found of various sizes, and 
variously grouped. Perfect crystals have seldom been found here of more than two or three 
inches in length, while those of from three quarters of an inch to an inch are very abundant. 
