276 DESCRIPTIVE MINERALOGY. 



are from twelve to sixteen inches in circumference. He describes tlicm as slightly rhomboi- 

 dal prisms.* The crystals which I have seen are right rhomboidal prisms, with angles of 

 about 105° and 75°. Sometimes, however, they approach the rhombohedral form, and at 

 others again they are nearer to right rectangular prisms. The great diversity in crystalline 

 form, and the bent and irregular appearance of the crystals themselves, lead me to believe 

 that they have undergone changes since their original formation. Dr. Thomson suggests that 

 they may be crystals of killinite, rather than of serpentine ; but killinite melts by the blow- 

 pipe, which is not the case with our mineral. The associates of these crystals are crichtonite 

 and spinelle. The same mineral also occurs massive at this locality. 



In the vicinity of the village of Amity, there is a bed of verd antique, which is supposed 

 to be of considerable extent ; and on the east side of Long pond there is a large vein, the 

 breadth of which is unknown. Its colour is dark oil-green, approaching to black. 



Putnam County. In Phillipstown, five miles south of the village of Fishkill, serpentine 

 of almost every variety occurs in a bed of white limestone. It is sometimes translucent, has 

 the conchoidal fracture, and exhibits various shades from yellow through yellowish green to 

 blackish green. Sometimes it is disseminated through the limestone in small grains, which 

 occasionally have little circles of amianthus around them. There is also a slaty variety which 

 has a dark green colour, breaks into irregidar four-sided prisms, and is hard and compact. 

 Another variety is of a greenish white colour, is harder than the preceding, and is fusible 

 upon thin edges by the blowpipe. It quite closely resembles nephrite. But it is evident from 

 an inspection of the locality, that however different the specimens may appear in the cabinet, 

 they all belong to the same species. Indeed one variety passes into another by almost imper- 

 ceptible gradations. All the differences which are here observable, are undoubtedly owing to 

 foreign admixture. A portion of feldspar, or tremolite, or both, has replaced the serpentine, 

 and thus produces those differences in character and appearance to which 1 have referred. 

 This is another of those facts which should put mineralogists upon their guard in the an- 

 nouncement and description as new, of those minerals which differ from known ones princi 

 pally in slight variations in chemical composition. 



The verd antique, which is found at this locality, has not heretofore been obtained in blocks 

 of sufficient size and solidity to answer the purpose of a marble. 



There is a locality of serpentine in the same town with the preceding, about ten or eleven 

 miles north-northeast of Peekskill, and about three quarters of a mile east of Horton's pond. 

 The rock is of a blackish green, fine grained, and sometimes coarsely crystalline. It is yel- 

 lowish on the weathered surface, and is associated with steatite. It seems to be sufficiently 

 abundant to warrant its employment as a marble. t 



Another locality, which is deserving of particular notice, is Brown's quarry, near Pine 

 pond, and a mile and a quarter north-northwest from the county poor-house. It is dark 

 coloured, from dark green to black, and varies in structure from compact to coarsely crystal- 



• American Journal of Science. IX. 242. t Mather. New-York Geological Reports, 1839, 



