CARBONATES 



tin- mo>t lieaiitiful specimens in the Tinted St.-ites are obtained 

 at Bislier, Ari/ona. The ma>-i\e Landed variety ocmr> in the 

 I'rals in Russia, where 

 it is much pri/ed as an 

 unialiiental stone, used 

 in the veneering of 

 vases, talile tops, and 

 decorations in build- 

 ing. The large in- 

 terior columns of St. 

 Isaac's Cathedral at 

 St. Petersburg are of 

 malachite. 



Malachite is also a 

 valuable ore of copper. 



Artificial malachite 

 is formed upon heat- 

 ing a solution of cop- 

 per bicarbonate. 



FIG. 453. Malachite with Concentric Bands of 

 Various Shades of Green. Bisbee, Arizona. 



AZURITE 



Azurite. Chessylite ; Basic copper carbonate, Cu(OH) 2 . 2 (Cu- 

 C0 3 ) ; CuO = 69.2, CO 2 = 25.6, H 2 = 5.2 ; Monoclinic ; 

 Type, Equatorial; a:b:c = .850: 1:1.880; P = 87 36' = 

 001 A 100; 100 A 110 = 40 21'; 001 A 101 == 44 46'; 001 A 011 

 = 41 21'; Common forms, c (001), a (100), m(110), p (021) ; 

 Twinning plane v (201) ; Cleavage, p perfect, a less so; Brittle; 

 Fracture, conchoidal ; H. = 3.5-4 ; G. = 3.77-3.83 ; Color, azure- 

 blue to deep blue ; Streak, smalt-blue ; Luster, vitreous to dull ; 

 Translucent to opaque; Optically (+) ; Axial plane perpendicular 

 to 010; Bx aA c = - 12 36'; 2E = 151. 



B.B. Like malachite. 



General description. Well-developed crystals are more com- 

 mon than those of malachite. They are varied in habit, and 

 highly modified, often tabular combinations of the base and unit 

 prism with a pyramid and dome, with the base striated, as at Bisbee, 

 Arizona. Peculiar complex aggregates, two inches in diameter, 

 some rhombohedral, others rounded, occur in the claylike pockets 

 in the Copper Queen mine, Bisbee, Arizona ; also at Chessy, France. 



