SILK 'ATI'S, TITANATES, ETC. f,n:j 



CHRYSOCOLLA 



Chrysocolla. A hydrous jnetasilicate of copper, CuSiO 3 . - 

 J 1 1 < ) ; CuO = 45.2, SiO 2 = 34.3, H 2 O = 20.5 ; Cryptocrys- 

 talline; Brittle; Fracture, conchoidal ; H. =2-4; G. = 2-2.4 ; 

 Color, shades of blue and green passing into black by oxidation ; 

 St ivak, white when pure ; Luster, vitreous to earthy ; Transparent 

 to earthy. 



B.B. Decrepitates, infusible but yields a copper flame. Re- 

 duced with soda, borax, and a little coal dust, yields copper 

 buttons. In the closed tube blackens and yields water. Decom- 

 posed with HC1 with the separation of silica, but without gelatiniz- 

 ing. 



General description. Occurs in crusts, botryoidal, or filling 

 veins and seams in the gangue rock of copper deposits. It is often 

 impure from an admixture of silica, when it will appear much harder 

 than 4. It becomes black from the formation of oxides. 



Chrysocolla is a mineral deposited from the percolating waters 

 which carry copper and silica, and is characteristic of the zone of 

 oxidation. It is therefore associated with the superficial areas of 

 most copper deposits. 



Fine specimens have been obtained at Bisbee, Arizona; at 

 Somerville, New Jersey, and in the Lake Superior copper region. 



When in sufficient quantity it is an excellent copper ore. It is 

 often polished and sold as an imitation turquoise. 



TITANITE 



Titanite. Calcium titanosilicate, CaTiSiO 6 ; CaO = 28.6, 

 Ti0 2 = 40.8, Si0 2 = 30.6; Monoclinic; Type, Digonal Equa- 

 torial ; a : b : 6 = .7546 : 1 : .8543 ; p = 60 17' = 001 A 100 ; 100 A 

 110 = 33 14'; 001 A 101 = 65 57'; 001 A Oil = 36 34'; 001 A 

 102 = 21 ; 001 A 111 = 38 16' ; Common forms, c (001), m (110), 

 n(lll), x(102), a (100), s (021) ; Twinning plane 100, both con- 

 tact and penetrating, other twins rare; Cleavage, prismatic dis- 

 tinct ; Brittle ; Fracture, subconchoidal ; H. = 5-5.5 : G. = 3.4- 

 3.6 ; Color, brown, yellow, gray, green, rose-red to black ; Streak, 

 white to pale brown; Transparent to opaque; a = 1.887; p = 

 1.894; -y = 2.009; y-& = .122; Optically (+) ; Axial plane 

 = 010; Bx a ,c = 51 in front; 2V = 27 30'; 2E = 52 30'. 



