LIME. 
223 
Rensselaer County. Crystals assuming the lenticular form, but of small size, have been 
found in fissures in the rock, near Troy. 
Rockland County. The excavations for the New-York and Erie 
railroad at Piermont, have exposed veins of trappean minerals of seve¬ 
ral kinds. Associated with these are found minute crystals of calca¬ 
reous spar, which sometimes have the form of the scalene dodecahe¬ 
dron ; and at others, nearly approach the cube, cuboide of Haiiy. Fig. 
80. h on h 87° 48'; h on hf 92° 12k In my specimens, these crystals 
are associated with stilbite. 
At Tompkins’ limestone quarry near Caldwell, several very inte¬ 
resting forms of calcareous spar have recently been found. Indeed 
this promises to become one of our most important localities. The 
crystals are often doubly terminated, and vary in size from being 
minute, to two or three inches in length. They are often highly finished and perfect; most 
commonly, however, they are grouped, and exhibit only a single termination. The colours 
are white and yellowish ; translucent to opaque. The forms which I have observed are the 
Fig. 83. 
binaire of Haiiy (Fig. 69); the modification, Fig. 81 ; the dodecaedre of Haiiy (Fig. 62); the 
same with the edges replaced at the upper part by triangular planes, Fig. 82 ; the metastatique 
of Haiiy (Fig. 60), and a modification similar to Fig. 78 ; together with a twin of the same, 
Fig. 83. The terminal planes of Figs. 62 and 82 often have a convex form, which extends 
also to the sides of the prisms ; it is hence very difficult to determine the exact value of the 
replacing planes. 
To the above may be added the following, which have also been found at this locality : 
