SILICA. 313 



blowpipe, or only at the thin edges, which are rounded, and become of a dark colour ; and it 

 may by this character be distinguished from tremolite, which it often resembles. This speci- 

 men contains grains and crystals, which are probably chromate of iron. 



The mineral called anthophyllite, from Rye in Westchester county, is probably tremolite ; 

 and the same remark will apply to that found at Smithtown on Long Island. 



In Massachusetts, according to Prof. Shepard, this mineral is found at Chesterfield and 



Blandford, associated with quartz in mica slate ; and in Connecticut, with tourmaline and 



iolite, at Haddam. 



« 



HYDROUS ANTHOPHYLLITE. 



Hydrous Anthophyllite. Thomson. — (Formerly known by the name of Radiated or Stellated Asbestus.) 



Description. Colour white, greenish yellow or bluish grey. It occurs in plates, or very 

 imperfect crystals diverging from various centres, or scopiform. The fibres are separable 

 from each other, but more imperfectly than asbestus. Lustre silky. Opaque. Sectile, and 

 has a soft feel. Hardness 2.5. Specific gravity 2.91. Infusible by the blowpipe. 



Composition. Silica 54.98, magnesia 13.38, peroxide of iron 9.83, protoxide of manga- 

 nese 1.20, potash 6.80, alumina 1.56, water 11.45 (Thomson). 



LOCALITIES. 



Dutchess County. There is a locality of this mineral in the town of Fishkill, about five 

 miles southeast of Stormville, on the land of Mr. Peck. It occurs in fibres forming radiated 

 masses of a white and bluish grey colour, in a talcose rock. 



New-York County. Hydrous anthophyllite has been found in place on the west side of 

 the island, between the 10th avenue and the Hudson, and between 57th-street on the south 

 and 63d-street on the north. Here the strata are nearly vertical ; the width of the bed at 

 right angles to the strike, varying from three to thirty rods. Dr. Gale states that the granite 

 lying on the west, and the gneiss on the east of the rock in question, come in complete con- 

 tact with it without intermixing.* 



This mineral is also found in bowlders in various parts of the island. The fibres are some- 

 times long and parallel ; at others, short and radiated or interlaced. The true composition of 

 this mineral was first pointed out by Dr. Thomson, who received his specimens from New- 

 York. 



" Ifew-York Geological Reporti, 1839. 



MiN. — Part II. 40 



