360 



DESCRIPTIVE MINERALOGY. 



Greene County. Rock crystal is often found in seams and veins in the slate in various 

 parts of this county. The best locality, however, at present known, is at Diamond hill, in 

 the village. The quartz is imbedded in a stiflf clay, between layers of the slate. A great 

 variety of crystaUine forms have been found at this place. Crystals are said to have been 

 here obtained, weighing two or three pounds. They sometimes had cavities containing a 

 hquid, a bubble of air, and some black or brown particles. In one specimen the cavity was 

 five-eighths of an inch long and a quarter of an inch wide, the bubble occupying nearly half 

 the cavity.* 



The specimens recently found at this locality will not by any means compare in beauty 

 with those which have been obtained in Herkimer county, but many of them present very 

 interesting modifications. They are seldom limpid throughout, and a large majority of the 

 specimens are imperfect. They seem, however, to be still abundant in the clay-filled cavities 

 of the slate. The forms which I have observed here, are those represented as follows, viz : 



Fig. 130, prisTne of Haiiy (p. 257.) 



The rhomhifere of Haiiy, similar to the preceding, with the addition of the rhomboidal 

 truncations of the alternate, lateral solid angles. Fig. 131. P on 5, or « on s 151° 7'; r on s, 

 or r' on « 142°. 



The same as Fig. 130, but having two opposite sides of the prism and the adjacent pyra- 

 midal faces unduly extended : prisme comprime of Haiiy, Fig. 132. 



Prisme sphalloide of Haiiy, Fig. 133. 



Fig. 131. 



Fig. 132. 



Fig. 133. 



 ClcavelancTs Mineralogy. 



