BARYTA. 207 



Schoharie County. In the town of Carlisle, about eight miles northwest of the court- 

 house, the fibrous variety occurs in considerable abundance between the layers of a dark 

 coloured slate. The mineral has a white, greyish-white, or bluish-white colour ; is delicately 

 fibrous, and often contains a large proportion of carbonate of lime. Indeed it seems to pass 

 into the fibrous carbonate of lime by almost imperceptible gradations. The specific gravity 

 of the purest specimens varies from 4.014 to 4.320, but even these usually effervesce slightly 

 in acids. The veins of this mineral are from a quarter of an inch to an inch and a half in 

 width. The fibres are parallel, and have a lustre between resinous and pearly. The mineral 

 is sometimes translucent, and seldom perfectly opaque. It seems to undergo some change 

 in its appearance by exposure to the atmosphere. This locality was first examined by Prof. 

 Eaton and Lieut. Pomeroy. The first gentleman pronounced it to be heavy spar.* It seems 

 to have been previously mistaken for celestine. 



Heavy spar also occurs associated with strontianite, in the water limestone, in the vicinity of 

 Schoharie court-house. In such cases it is generally found in the form of laminae, which 

 cleave readily, and sometimes present two or more faces of the primary prism. In all the 

 specimens which I have examined, it is mixed with carbonate of lime, and also with portions 

 of strontianite. Indeed, these two substances are so abundant in this limestone that the 

 massive specimens of heavy spar are seldom pure. 



The Calstronbaryte of Prof. Shepard, in my opinion, is nothing more than one of these 

 mixed minerals. It is said to be composed of 



Sulphate of baryta, 65. 55 



Carbonate of strontia, 22. 30 



Carbonate of lime, 12.15t 



I might also have added another new mineral from the vicinity of Schoharie ; as a specimen 

 which I supposed to be the calstronbaryte gave upon analysis somewhat different results. 

 But I soon ascertained that this composition was not constant, and that in this case diffe- 

 rence in chemical composition was not to be relied on as a ground of specific distinction. 

 As in the fibrous variety from Carlisle, scarcely any two specimens agree in this respect. 

 Mineralogists who visit this locality, will at once see, from the manner in which the heavy 

 spar occurs in the water limestone, from its imperfect crystallization, and from the minerals 

 with which it is associated, the causes which influence its chemical composition, and will hence 

 adopt with much caution the new species whose characters depend upon slight differences in 

 the proportions of these widely diffused and constantly associated mineral substances. 



• Ammam Joitmal of Science, II. 173. f Shepard. Amtricm Journal of Science. XXXIV. 161. 



