366 On the Strontianite of Schoharie, (N. Y.) 



The compound crystals, (and they are nearly all such) are 

 represented by fig. 2. The face of composition is apparently par- 

 allel with the vertical edges between c and c, fig. 1 . The individuals 

 project beyond the face of composition only on one side ; but the 

 composition is very often repeated in parallel laminae. 



Still another variety of Strontianite comes, apparently from the 

 same place. It occurs in cavities or geodes, surrounded by blueish 

 Calcareous Spar, but without the Heavy Spar ; and offers the largest 

 and the best pronounced crystals I have yet seen. The form of the 

 most perfect is represented by fig. 3, though planes c c are rarely 

 very distinct. They are an inch in length, (in the direction of the 

 edge between a a,) and nearly half an inch in thickness : color, -blu- 

 ish or reddish grey ; translucent. Surface, P is streaked parallel 

 with its edge of combination with o. The inclination of a to a = 120° 

 and that of a to P = 120°. I have not seen cavities containing 

 above four or five of these crystals at once. 



The most singular crystallization, and one most likely to be over- 

 looked from the smallness of the crystals, and their want of lustre, 

 is that in octahedra with rectangular bases, the longer edges of the 

 base being to the shorter as five to one. The smaller pyramidal fa- 

 ces, I take to be the lateral planes of the primary form, and the broad- 

 er ones to be the secondary faces, arising from the truncation of the 

 oblique angles of the primary crystal. These crystals vary in length 

 from { to J of an inch, are dull, greyish white, and with rough faces, 

 often covered by crystals of Iron Pyrites. They are so thickly 

 disseminated through the clayey limerock as to form two thirds of 

 its mass, and render it very difficult of fracture. The form of its 

 crystal can scarcely be detected, except at the surface of those 

 masses which have been weathered, when their rough and dull faces 

 appear, resembling the crystals of Fontainbleau Limestone. 



The last and the most interesting variety, if we consider the am- 

 biguity its determination presents, and the immense quantity in 

 which it exists, is the milk-white, massive variety. Mr. Bonny en- 

 closed a large sample in his second case, accompanying it with the 

 label " Marble. In great quantities. From the gravity I think it 

 is Sulphate of Barytes." It was certainly natural from its color to 

 call it Marble, and from its weight to suspect it to be Heavy Spar. — 

 And I confess I should have been slow to pronounce it Strontianite, 

 except that the cleavage indications of Heavy Spar and of Celestine 

 were both wanting, and that it closely resembled a massive variety, 



