No. 200.J 
139 
Granite. 
This rock occurs in place on Staten Island, on the shore opposite 
Nautilus Hall J at the Quarantine. It is coarse grained, composed of 
white and smoky quartz, red and gray feldspar, and mica. It is seen only 
over a space of a few square rods, and is covered by the deposits belong- 
ing to the erratic block group. It is not of a suitable texture for a 
building material, and cannot be applied to any useful purpose, except 
as a rough wall stone. 
Serpentine. 
This rock forms the main ridge of hills on Staten Island, and extends 
from New Brighton to a little west of Richmond, a distance of eight 
miles. It ranges N. 20° E. and S. 20*^ W. and the prolongation of the 
line of direction strikes the Serpentine hills of Hoboken. The serpen- 
tine rock assumes a great variety of aspects, from black to nearly white, 
and from compact to earthy. Some of the talcy varieties are called 
soapstone by the people. Talc, carbonate of magnesia, and hydrate of 
magnesia, abound in it, and the rock might be used with profit in ma- 
king magnesian salts. Asbestus and amianthus are not rare in it. This 
rock sometimes assumes an aspect almost like trap, but its specific gra- 
vity is much less. 
Amianthus and asbestus are constant associates of our serpentine 
rocks, and on Staten Island it is possible that it may be obtained in 
quantities for useful purposes. 
Dr. James Pierce described the amianthus of Staten Island in 1818.* 
He states that " it breaks up like flax, and may be spun and woven 
without the aid of moisture; and in respect to tenacity, flexibility, and 
length of fibre, it may be considered the best found in this country, and 
perhaps equal to any hitherto discovered." Prof. Silliman remarks up- 
on the above, " the specimen of amianthus referred to in Mr. Pierce's 
communication, is uncommonly beautiful. The fibres measure 12 and 
15 inches in length, and are as soft and flexible as fine human hair."t 
The value of this material is well known. It has been principally em- 
ployed in making incombustible cloth for firemen's dresses. It would 
be more extensively useful in making indestructible paper for public re- 
cords. The amianthus of Staten Island is believed to have been used 
only as mineralogical specimens. 
* Am. Jour, of Science, I. p. 54. f Idem, p. 55. 
