QUARRIES IN FRANKLIN COUNTY. 81 
of abundance: Potash feldspar (microcline and orthoclase), clear 
quartz, soda-lime feldspar (oligoclase), black mica (biotite), and 
while mica (muscovite), together with accessory garnet, magnetite, 
and apatite. The general whiteness of this rock is due to the quartz 
not being smoky as in most granites, and also to the whiteness of the 
feldspars, which is thus visible through the quartz. The feldspars 
are mostly unaltered. The following chemical analysis of this 
granite, made by E. T. Rogers, was reported by Prof. John E. Wolff, 
of Cambridge, Mass., in 1892 : « 
Analysis of </r<iiiilc from quarry at North 'lay. 
SiO. (silica) 71.54 
Ti0 2 (titanium dioxide and Fe,0 3 (?)). — 0. 84 
AL0 3 (alumina) 14.24 
Fe 2 O s (ferric oxide). 0.74 
FeO (ferrous oxide) ___ 1.18 
CaO (lime) 0.98 
MgO (magnesia) _ 0.34 
Na 2 (soda) __. 3.39 
KX> (potash) 4.73 
H.O (water, at red heat) 0.61 
S (sulphur) Trace. 
COo (carbon dioxide) Trace. 
98. 59 
The same analyst finds the specific gravity 2. 639. A test of the com- 
pressive strength of this granite, made for the company at the Water- 
town Arsenal in 1892, shows that the cube cracked at 15,720 pounds 
per square inch and was destroyed at 16,310 pounds per square inch. 
An earlier test of the same granite with somewhat different results 
was made at that arsenal on May 6, 1882. b It does not take a very 
good polish, owing to the abundance of mica and the large size of its 
plates. The North Jay granite was also described by M. E. Wads- 
worth in 1878.° 
The quarry, opened in 1872, consists of three openings, known by 
the name of " Upper," " Lower,'' and " Bowlder." The upper quarry 
measures about 425 feet from north to south by 200 feet from east to 
west and has an average depth of 20 feet. The low T er one, adjacent 
to it on the west, measures 500 feet from north to south and 350 feet 
from east to west, with an average depth of about 35 feet. These 
openings are on the west side of a north-south ridge. The bowlder 
quarry, a little north of the other two, is about 150 feet square and 
20 feet deep. , The upper and lower quarries are separated by a mass 
See Nineteenth Ann. Rept. U. S. Geol. Survey, pt. 6, continued. 1898, pp. 218, 219. 
* Eighteenth Ann. Rept. IT. S. Geol. Survey, pt. 5, continued, p. 961. 
c Proc. Boston Soc. Nat. Hist., vol. 19, pp. 237-238. 
3495— Bull. 313—07 6 
