34 Mineralogy of New York. 



val in which the process of crystallization was suspended, com- 

 menced again to enlarge — owing perhaps to a new supply of the 

 calcareous solution : — but at this time the crystal is so changed 

 in condition, or in its attracting influences, that the laminae added 

 to the rhombohedral faces, were no longer modified as before, and 

 consequently, instead of enlarging the face a, they extend above 

 it, and form a border around it. The calc spar of this region is 

 often transparent and presents yellow, rose and amethystine tints 

 in addition to the more common shades. 



Apatite. — The apatites of St. Lawrence Co., are remarkable for 

 their size. One from Hammond measured nearly a foot in length 

 and weighed eighteen pounds. The crystals are usually the six- 

 sided prism with simple pyramidal terminations. Very often the 

 faces and edges are rounded, and some crystals are curved or 

 bent. Deep and pale green and blue are the common colors. 



Magnesian Carbonate of Lime. — Prof. Beck found the Pearl 

 spar of Lockport, to consist of carbonate of lime 59*00, carbonate 

 of magnesia 39 50, carbonate of iron 1*50. The variety called 

 Gurhofite from Phillipstown — a white compact rock, having a 

 semi-opaline appearance and a fracture like porcelain, consists of 

 carbonate of lime 6675, carbonate of magnesia 26-50, silica 6*75. 

 An allied variety from the Quarantine, Richmond Co., gave car- 

 bonate of lime 52-75, carbonate of magnesia 4225, insoluble mat- 

 ter chiefly silica 5-00, with traces of oxyd of iron. Sp. gr. =2*7 J 2. 

 It is a tough rock and is difficult of solution, except when finely 

 pulverized. 



Magnesite. — Under this name Prof. B. includes the marmolite 

 of Nuttall, which is properly a foliated serpentine, as it is identi- 

 cal with it in composition ; also kerolite and meerschaum. A 

 mineral from Westchester sometimes labelled kerolite, presenting 

 thin brittle plates of a white or green . color, subtranslucent and 

 somewhat resinous in lustre, afforded him, silica 40-50, magnesia 

 3S00, water 21-00, with a trace of iron. This composition agrees 

 nearly with that of serpentine, of which this mineral appears to 

 be a variety. Another specimen from the Quarantine, Richmond 

 Co., where it occurs in thin seams in serpentine, gave nearly the 

 same composition. A variety from Stony Point, Rockland Co., 

 afforded him, silica 37.40, magnesia 32.56, oxyd of iron 10.05, 

 water 14.60, alumina 5-35, with a trace of oxyd of manganese. 

 It occurs with other magnesian minerals in trap, forming narrow 



