CARBON \TI S 



[>;||>CT. Ill-ohll>lr ill dlllllr IK 'I. l)Ut rHVrvocc- id hot, 



acid. Tin- concentrated IK'l solution yields :i \vhiii- precipitate 

 with H,SO 4 (CaSO 4 ). 



FIG. 444. Dolomite. Traversella, Switzerland. 



General description. In habit, generally in simple rhombo- 

 hedrons which may occur in complex aggregates, with curved, 

 warped, or saddle-shaped surfaces ; this warped appearance of the 

 crystal faces may occur in any of 

 the species of the rhombohedral 

 group of carbonates, but is es- 

 pecially characteristic of dolo- 

 mite and siderite. Dolomite, 

 while placed in the calc te group, 

 is not an isomorphous mixture 

 of the two carbonates, but a 

 double salt. This : s not only 

 shown by the difference of sym- 

 IIK t ry, but by the specific gravity 

 of dolomite (2.85) being higher 

 than would be required by the 

 molecular mixture (2.843). That magnesium carbonates do enter 

 the calcite molecule and form isometric mixtures is shown by 



Fio. 445. Dolomite Var. 

 Teruel, Spain. 



Teruelite. 



