GEOLOGY AND PALEONTOLOGY OF THE SCHOHARIE VALLEY 359 



through the calcareous spar. The color of the strontianite is 

 white, or slightly tinged with grey or blue; and it is semitrans- 

 parent or translucent. 



A second variety quite different in general appearance from the 

 first .... is massive, indistinctly lamellar, and approaching 

 to impalpable. Color, milk white, rarely with a delicate and 

 almost imperceptible shade of green. This variety occurs in 

 veins, from a quarter of an inch, to two inches wide, and is em- 

 braced directly by clayey limestone. Rarely, it is traversed by 

 large lamellae of heavy spar, which are easily distinguishable by 

 their crystalline texture. Very small quantities of calcareous 

 spar attend this variety occasionally, but it is not of a blue color. 

 The circumstances of its deposition appear to have been different 

 from those of the first variety 



A third and more interesting variety appears to form 



a vein of considerable size, the mass of which resembles the last 

 variety in structure and color, as well as being traversed occasion- 

 ally by lamellae of heavy spar. But upon one side of the masses, 

 tabular crystals of strontianite single and compound, an inch in 

 length, and one third of an inch wide, are thickly implanted on a 

 surface of transparent crystals of calcareous spar. The calcareous 

 spar is in large crystals of the form of the metatastique. The 

 strontianite is partially coated by a white powder, as if it were 

 suffering decomposition,^ and the crystals of calcareous spar are 

 covered completely by little fissures and cavities, where the 

 strontianite once penetrated them. It is observable however, that 

 the large crystals of strontianite still remaining are connected 

 among themselves, as also to the mass of massive strontianite be- 

 low. Small transparent crystals of quartz are also disseminated 

 through the calcareous spar, but no iron pyrites is present. . . 



Still another variety of strontianite comes, apparently from the 

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

 calcareous spar, but without the heavy spar; and offers the largest 

 and the best pronounced crystals. . . They are an inch in 

 length, and nearly half an inch in thickness; color, bluish or red- 

 dish grey; translucent. 



The most singular crystallization, and one most likely to be 

 overlooked from the smallness of the crystals, and their want of 

 luster, is that in octahedra with rectangular bases, the longer 

 edges of the base being to the shorter as five to one. The smaller 



^Tbe only suggestion that offers itself to my mind in explanation of this 



incipient decomposition is, that sulfuric acid may have been produced 



from the oxidation of the sulfur in the iron pyrites, and have formed a 



slight coating of sulfate of strontia upon the crystals of the strontianite. 



[C. U. S.l 



