PHYSIOGRAPHY. 173 



Dolomite. 



In the U. States the Rhomb-spar variety or bitter-spar, occurs abun- 

 dantly at numerous places in R. Island, Massachusetts and Vermont, im- 

 bedded in common Talc or its variety, steatite ; as at Roxbury, (Vt.) where 

 it occurs in large, yellow, transparent crystals, imbedded in greenish 

 transparent Talc ; at Srnithfield, (R. I.) where it occurs in large grained, 

 easily cleavable individuals, associated with white Talc in Calcareous 

 Spar or limestone, and rarely in very perfect implanted rhomboids of 

 small dimensions. The Pearl-spar exists abundantly both of a white 

 color, and with a delicate pink tinge, at Lockport. (N.Y.) where it is as- 

 sociated with Calcareous Spar, Celestine, and Gypsum in geodcs, 

 occurring in transition limestone. The brown-spar is found at nume- 

 rous places in New York and Ohio, where it occurs in greywackes and 

 secondary limestones, in the form of veins and seams. The massive va- 

 riety of Dolomite constitutes extensive beds in Litchfie'd county, (Conn.) 

 and in the south western towns of Massachusetts. 



6. Dolomite is often employed as a marble, and rarely in the produc- 

 tion of quick lime. 



APPENDIX TO DOLOMITE. 

 i. Eumetric Carbon- Spar. BREITHAUPT. 

 Pon P=106 11'. 



Cleavage parallel with P uncommonly perfect and easy. 

 Hardness = 5-0, (scale of BREITHAUPT.) 

 Sp. gr. =2-9177, a cleavage crystal. 



The Eumetric Carbon-Spar embraces only the beautifjl twin-crystals, 

 above alluded to, from Traversella in Piedmont. 



ii. Tautoklinous Carbon- Spar. BREITHAUPT. 

 Pon P=10S 10' 40". 

 Cleavage parallel with P perfect. 

 Hardness = 4-75 ... 5. (scale of BREITHAUPT.) 

 Sp. gr. =2-9633. ) Fragments of cleavage crystals from the 



2 9644. 5 mine of Beschert GlQck in Freiberg. 

 Color reddish, or greyish-white. 



It occurs at Freiberg, Johann-Georgenstadt, and probably the brown- 

 apar of Schnecberg belongs to the present species. 



Hi. Kryptose Carbon- Spar. BREITHAUPT. 

 Pon P = 106 19'. 

 Cleavage parallel with P, but not very perfect. 



15* 



