sru'HATi:s. CHBOMATES, i-:TC. 533 



parent to opaque ; a = 1.877; P = 1.SS2; y = 1.894; y - a = 

 .017: Optically ( + ); Axial plane, 010; Bx. = 4; 2V =66 47'. 



B.B. Decrepitates and fuses at l.f>. In R. K. on coal reduces 

 to lead and yields a lead coat; fused with soda and a little coal dust 

 yields a sulphur reaction with silver. Insoluble in acids. 



General description. Crystals often tabular in habit, combi- 

 nations of c, m, and d, or elongated similar to barite, with which it is 

 isomorphous. Transparent crystals have a particularly high 

 luster, as the specimens from Monte Poni, Sardinia, where they 

 occur implanted on galena. Anglesite is named for the island of 

 Anglesra, where it was first observed associated with an earthy 

 limonite. 



Anglesite is an oxidation product associated with lead ores, 

 particularly with galena, and when in sufficient quantities it is a 

 valuable lead ore. 



CROCOITE 



Crocoite. Lead chromate, PbCrO 4 ; PbO.= 68.9, Cr0 3 = 

 31.1; Monoclinic ; Type, Digonal Equatorial ; a:b: c = .9603: 

 1 : .9158 ; p = 77 33' = 001 A 100 ; 100 A 110 = 43 10' ; 001 A 101 = 

 37 41'; 001 A Oil = 41 48'; 111 A 111 = 60 50'; Common forms, 

 b(010), c(001), m(110), t(lll), v(lll); Cleavage, m distinct, 

 a and c less so ; Brittle ; Fracture, uneven ; H. = 2.5-3 ; G. = 5.9- 

 6.1; Color, bright hyacinth-red; Streak, orange-red; Luster, 

 adamantine to vitreous ; Transparent to translucent ; P = 2.42 ; 

 Optically ( + ) ; Axial plane, 010; Bx^.c = 5 30' ; 2 V = 54 3'. 



B.B. Fuses at 1.5, and reduced on coal with soda yields lead 

 buttons and a lead coat. In S. Ph. yields a green bead in both 

 flames (Cr). In the closed tube blackens and decrepitates, but 

 recovers its original color on cooling. 



General description. Crystals are elongated parallel to the 

 vertical axis with striations on the prism faces lengthwise. At 

 times apparently rhombohedral or granular. 



Crocoite was described as a new mineral from the Urals in Russia 

 by Lehmann in 1762, where it occurs associated with quartz crys- 

 tals. It was in crocoite that Klaproth and Vauquelin independ- 

 ently in 1797 discovered the metal chromium. 



Beautiful long, slender crystals with nearly a square cross sec- 

 tion have been found at Dundas, Tasmania. It also occurs in 



