No. 275. 1 193 
6, Hydrous Jlnthophijllite, This rock has been familiarly known for 
many years in this vicinity under the name of radiated asbestos rockj 
but was known only as a boulder found in considerable abundance in 
various parts of the city, and as far north as 15th or 20th-street. Its 
geological place was not, however, known at that time; and as its true 
mineralogical character was somewhat doubtful, Dr. Torrey sent speci- 
mens of it to Professor Thomson, of Glasgow, who analyzed and pro- 
nounced it anthophyllite; but as it contained a much larger proportion 
of water than had usually been found in this mineral, Dr. Torrey pro- 
posed to prefix the term hydrous, which has been generally adopted. 
This rock has been found in place on the west side of the island, be- 
tween 10th avenue and the Hudson, and between 57th-street on the 
south, and 63rd-street on the north. Here the strata are nearly vertical; 
the strike is NNE; the width of the bed at right angles to the strike 
varies from 3 to 30 rods. It commences at 57th-street, within 30 or 
40 feet of the avenue, and runs obliquely to the streets crossing the 
1 1th avenue near 60th-street, and runs out at the river on 63rd-street. 
It is remarkable that the granite lying on the west, and the gneiss on 
the east of the rock in question come in complete contact with it with- 
out intermixing. So remarkable is the line of separation on the side 
next to the gneiss, where there is the best opportunity to examine the 
two, that within the space of three inches each rock possesses all of its 
own peculiarities, with none of those of its neighbor. The mineral 
character of this rock varies much in different parts of the bed. In the 
southeast portion where it approaches nearest to 10th avenue it exhibits 
little or no stratification, is very dark coloured, and has a tabular struc- 
ture. In the same vicinity are found masses of serpentine and lime- 
stone intermixed, exhibiting a porphyritic appearance, the serpentine 
appearing green and the limestone white. Again near the middle of 
its course, or near where it crosses the 11th avenue, it becomes lighter 
in colour, more fibrous and scopiform in structure; but the fibres are 
large, and in some instances approach the character of actynolite. 
Still lower down, following the strike towards the river, the same 
mineral character continues, except that the fibres are still finer, and 
the whole texture becomes softer and more like steatite; so that many 
years ago, before the rock was known to geologists, it was attempted 
to work this bed for a soapstone quarry, to be applied for similar useful 
purposes; but the material being too hard, the project failed. This 
rock has been found in boulders in all of the southern part of the island, 
and some are very large. On the west side they extend from the rock 
in place to 15th-street, In the middle division they have been found 
[Assem. No. 275,] 25 
