SILICA. 
271 
About a mile and a half north of Lewis corners, there is another locality. The mineral 
here is snow-white, and closely resembles that from Easton in Pennsylvania. It is associated 
with garnet and quartz, the latter of which gives a sharpness to the masses of tabular spar, 
which it does not usually possess. 
At Rogers’ rock, near the line between this and the county of Warren, tabular spar occurs 
with characters similar to those observed in the specimens from Willsborough. It is asso¬ 
ciated with garnet, adularia and common feldspar. 
The same mineral is not unfrequently found in loose masses in various parts of this county. 
It has thus been met with in the vicinity of Port Henry. As thus found, it has a greyish 
white colour, with a tinge of olive, and is highly translucent. It is associated with brown 
mica, and sparingly with scales of graphite.* 
Lewis County. In the town of Diana, about a mile from the Natural bridge, is a large 
deposit of tabular spar in the limestone. It is of a snow-white colour, has a vitreous lustre, 
and closely resembles some varieties of tremolite. Its apparent purity induced me to subject 
it to analysis. Its composition is as follows : 
Silica,. 51.90 
Lime,. 47.55 
Oxide of iron,. 0.25 
At this locality, the tabular spar is associated with green coccolite, and is exactly similar 
to the specimens which are found in loose masses in Oneida county. I have no doubt that 
this is the rock from which these bowlders have been detached. 
There is another locality nearer to the Natural bridge than the preceding, where the mineral 
is abundantly found in detached masses. Here, however, it is of a greyish colour, and the 
folia are not so large or beautiful, nor is the lustre so high. 
Oneida County. Large bowlders of tabular spar, associated with garnet, have been dug 
up in the village of Boonville. The specimens, as I have just stated, resemble those from 
Lewis county more nearly than those from Essex. The Essex county specimens are usually 
associated with garnet or colophonite, whereas those from Boonville and Diana have green 
granular pyroxene (coccolite) as their associate. I have compared specimens from the two 
localities, and find it very difficult to distinguish them. This is a fact of some interest in 
connection with the mode in which bowlders have been transported. Boonville is between 
forty and fifty miles directly south of the Natural bridge. These bowlders have been described 
by Prof. Plubbard, of Dartmouth College.! 
Shepard. American Journal of Science. XVII. 140. 
t American Journal of Science. XXXII. 230. 
