SILICA. 
305 
crumbled down, and left these crystals and the veins of asbestus exposed. Some barrels of 
asbestus have been obtained from Rogers’ farm, a mile from Patterson. By macerating the 
specimens in dilute muriatic acid, the dolomite is dissolved, and the asbestus is left in the 
form of white silky fibres closely interlaced. 
The variety amianthus, in thin seams, traverses the serpentine at Hustis’ farm in Phillips- 
town, five miles south of the village of Fishkill, on the stage road to New-York. It is white 
and yellowish white, and has a beautiful silky appearance. The fibres are fusible by the blow¬ 
pipe, after coiling at the extremities, into a white opaque mass ; they are readily fusible with 
borax. This mineral has been thought to be identical with the foreign picrolite ; but the latter 
is still an obscure species. 
At Cotton Rock, on the bank of the Hudson in Phillipstown, about three and a half miles 
below West-Point, between high and low water mark, beautiful specimens of asbestus have 
been obtained. The rocks here, according to Mr. Mather, are impure verd antique, serpentine 
with diallage rock, augite and granite. Veins of asbestus and delicate silky amianthus pass 
through the serpentine ; the latter having the appearance of cotton or raw silk, has given rise 
to the name by which this locality is known.* 
Richmond County. The varieties, asbestus and amianthus, are very abundant in various 
parts of this county, especially near the Quarantine. They are found associated with com¬ 
mon and steatitic serpentine, and other magnesian minerals. The hard asbestus, resembling 
chips of wood, occurs near the Pavilion hotel; it breaks into rhombic prisms having the form 
of hornblende. In the same vicinity there is rose straw-coloured amianthus, having the 
fibres between two and three feet in length. These fibres have the lustre and softness of silk, 
and may be spun or woven. As a locality of these varieties, this is one of the best in the 
United States, and is thought to be equal to any hitherto discovered. It was first made known 
to mineralogists by Mr. J. Pierce.f 
Rockland County. Small but imperfect crystals of black hornblende are common in the 
trap at Haverstraw, and in other parts of this county. The lamellar variety is abundant at 
Stony point; and actynolite of a dark green colour, the fibres being radiated, interlaced and 
imperfectly crystallized, occurs two and a half miles west of Grassy point, associated with a 
kind of serpentine marble. This locality is often known by the name of Montague's marble 
quarry ; but it is of little value, except for the cabinet specimens which it affords. 
Asbestus or picrolite is found in thin veins, associated with the soft serpentine or kerolite, 
in the trap dyke on the north side of Stony point. It has a greenish colour, a high silky 
lustre, and the fibres are extremely delicate. 
* Mather. New-York Geological Reports, 1839. f American Journal of Science. I. 54. 
Min. — Part II. 
39 
