SILICA. 



293 



Fig. 215. 



Fig. 216. 



One of the crystals found at this locality was nearly six inches in length, and ten inches in 

 circumference ; another was three inches long, and fourteen inches in circumference.* A 

 fine green coccolite is found in the vicinity of this locality. 



About two miles southeast of Greenwood furnace, this mineral, in the crystallized form, has 

 also been found. 



A mile northwest of the village of Edenville, pyroxene occurs in crystals of a dark green 

 or nearly black colour. The form is usually the eight-sided prism with three terminal faces, 

 but sometimes it is more complex. These crystals are associated with apatite, hornblende 

 and sphene, in calcareous spar. 



Two and a half miles north of Edenville, there occurs 

 an interesting variety of crystallized pyroxene. The 

 crystals are usually of a grey colour, rough on the sur- 

 face as if they had undergone partial decomposition. 

 Fig. 215 represents one of the forms, but the measure- 

 ments can not be completed from any of the specimens 

 which I have seen: Z on a; about 114° 26'; r on x 

 126° 36'; a: on a; 131° 8'. 



In Warwick mountain, we have the forms repre- 

 sented by Figs. 193, 206, 208 and 216. P on 5 150° 

 0'; sons 120° 38'. 



In the vicinity of the village of Amity in the town of Warwick, and of Fort Montgomery 

 on the Hudson, there are localities of crystaUized pyroxene ; but no forms, other than those 

 already noticed, have been observed. 



The lamellar variety is found, of great beauty, in the Forest of Dean, in the town of Mon- 

 roe. It is of a dark green and bronze colour, with a fine lustre and distinct lamellar structure, 

 yielding readily to cleavage in the direction of the primary prism. It is associated vrith 

 sphene and scapolite. Laminae may here be obtained of from four to six inches in diameter, 

 but they are sometimes so small and irregular that the mineral appears granular. 



Another beautiful variety of sahlite is found about three miles southeast of Greenwood 

 furnace. It exhibits a very distinct lamellar structure, and has a bronze or copper colour, and 

 often a metallic lustre. It closely resembles some of the specimens of so called hypersthene 

 from the northern part of the State. 



On the immediate bank of the Hudson, three miles above West-Point, the lamellar variety 

 occurs associated with quartz, black and bronze-coloured mica and feldspar. A specimen 

 from this locality was analyzed by Mr, Vanuxem. The specific gravity is about 3.24. Its 

 composition is 



* American Jmvmal of Science. VIII. 88. 



