Sll.K 'ATI-S, TITAN VI I S, 1 ,T< 



111.1 



Digoiial K<|iiatorial ; < 'ry-talline elements and habit like biotite ; 

 Cleavage, kisal perfect, micaceous, lamina- lough ;ili(l elastic; 



H. = 2.5-3; G. = 2.78-2.85 ; Color, yellowish brown, with me- 

 tallic-like reflections, al-o greenish to nearly colorless; Streak, 

 white; Luster, pearly; Transparent to t raii-liiccnt ; a = \.~>(\2; 

 p = i.uor, ; Y = 1.606; -y - a = .044 ; Optically (-) ; Axial 

 plane = 010; Bx.J-toOOl; 2E = 0-40. 



B.B. Whitens and fuses on the thin edges. Generally yields 

 no iron reactions with the fluxes. Decomposes with sulphuric 

 acid, leaving the silica in thin flakes. In the closed tube yields 



some water. 



General description. In 

 rough, six-sided crystals, 

 which are, however, better 

 formed than in biotite. 



It occurs, as a product of 

 metamorphism, in the crys- 

 talline limestones and dolo- 

 mites, as at Gouverneur, 

 New York; Newton, New 

 Jersey ; Franklin, New Jer- 

 sey ; and various other locali- 

 ties in the Middle States and 

 Ontario. Crystals from 

 Sydenham, Ontario, measure 

 five or six feet across the 

 base. 



In decomposition it resembles biotite, and commercially it finds 

 the same uses as muscovite. 



FIG. 510. Phlogopite. Rossie, New York. 



LEPIDOLITE 



Lepidolite. Lithia mica, H 2 KAl 3 (SiO 4 )3 . R 3 AlF(Si 3 O 8 ) ; Mono- 

 clinic ; Type, Digonal Equatorial ; Crystalline elements and form 

 as in muscovite; Cleavage, basal perfect, micaceous lamina) 

 flexible, elastic, and tough; H. = 2.5-4; G. = 2.8-2.9; Color, 

 pale pink, violet, gray, or yellowish ; Streak, colorless ; Luster, 

 pearly; Transparent to translucent; P = 1.597; y = 1.605; 

 y - p = .008 ; Optically (-) ; Axial plane -L to 010 ; Bx a * c = 5 ; 

 2E = 57-85. 



