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DESCRIPTIVE MNERALOGY. 



STRONTIANITE. 



[From Strontian in Scotland, where it was first found.] 



Strontiane Carbonalie. Haiiy. — Carbonate of Strontian. Ckaveland. — Strontites. PhUiips. — Green Carbonate 

 of Strontian. TTumiwn ? — Peritomous Baryte. Jameson. — Peritomcr Hal-Baryt. Mohs. — Strontianite. Ben- 

 dant, Shepard and Dana. 



Description. Colour asparagus green, yellowish brown, yellow- 

 ish, grey and white. Occurs regularly crystallized ; also massive, 

 fibrous and stellated. The primary form is a right rhombic prism. 

 Fig. 51. M on M' 117° 32'. Cleavage parallel with M, rather 

 perfect. Fracture in other directions uneven. Lustre shining, 

 glistening and pearly. More or less translucent. Brittle, and easily 

 frangible. Hardness 3.5. Specific gravity from 3.60 to 3.80. 

 Before the blowpipe, it does not fuse, but is converted on the sur- 

 face into an enamel, which assumes a dazzling whiteness, and gives the flame a reddish hue. 

 With borax, or biphosphate of soda, it fuses into a clear glass. It is soluble with efferves- 

 cence in nitric or muriatic acid ; and papers dipped into this solution, when dried, burn with 

 a red flame. 



Witherite or carbonate of barytes, which this mineral often closely resembles, has a higher 

 specific gravity, and melts before the blowpipe without changing the colour of the flame. 



Composition. When pure, this mineral is composed of carbonic acid 30, and strontia 70. 

 Its formula is SrO.COa. But as it occurs in nature, it usually contains small quantities of 

 lime, baryta, manganese, water, etc. 



Geological Situation. It occurs in veins of calcareous spar and galena, and in the 

 hydraulic limestone. 



Uses. This mineral is used in the preparation of the other salts of strontia. 



LOCALITIES. 



Jefferson County. Strontianite has been found in radiated masses on Muscolunge lake, 

 where it forms part of the matrix of fluor spar. It has a white and pale green colour, and is 

 fibrous. It is also said to occur at Chaumont bay, in this county. 



Schoharie County. It occurs in geodes and nests, sometimes of large size, in the hydrau- 

 lic limestone. The most remarkable locality is in the face of the hill about two miles from 

 the court-house. This variety has a snow-white colour, is compact, and susceptible of a 

 good polish. It was formerly mistaken for common white marble, its true nature having been 

 first pointed out by Dr. Emmons.* The specimens which I have examined are nearly pure 



* American Journal of Science, XXVII. 182. 



