COU'MBATKS, I'll" >H'l I.VI'I .S, \ ANADAT1.S 515 



DUFRENITE 



Dufrenite. Fe 2 (OH)jP0 4 ; a basic orthophosphate of iron ; 

 Fe*O 3 = 62.0, P 2 & = 27.5; H 2 O = 10.5; Orthorhombic ; Type, ? 

 ft: b:c = .8734:1:. 4262; 100. 110 = 41 8'; 011*011=46 

 10'; 001/101 = 26 1'; 001*011 = 23 5'; Common forms 

 a (100), b(010), m(110), e(011); Cleavage, macropinacoidal 

 distinct; Brittle; Fracture, uneven ; H. = 3.5-4; G. = 3.2-3.4; 

 Color, dark green to nearly black, brown and yellow by oxidation ; 

 St rcak, green ; Luster, dull to silky ; Subtranslucent to opaque. 



B.B. Fuses in R. F. and becomes magnetic. Powdered and 

 treated with H 2 SO 4 yields a green flame in O. F., or dissolved in 

 nitric acid shows phosphoric acid with ammonium molybdate. 

 Yields water in the closed tube and only iron reactions with the 

 fluxes. 



General description. Crystals are small and cubical in appear- 

 ance, but very rare, generally occurring as radiated or fibrous 

 masses with drusy surfaces. 



Dufrenite is a secondary mineral, precipitated from solutions 

 and associated with limonite deposits, as at Rockbridge County, 

 Virginia. It is also found as a crust in the green sand formations 

 of Allentown, New Jersey. By oxidation it becomes brown and 

 by loss of P 2 O 6 forms limonite. 



LAZULITE 



Lazulite. (Fe . Mg) A1 2 (OH) 2 (P0 4 ) 2 ; when Fe : Mg: : 1 : 2, FeO 

 = 7.7, MgO = 8.5, A1 2 O 3 = 32.6, P 2 O 6 = 45.4, H 2 O = 5.8 ; 

 Monoclinic ; Type, Digonal Equatorial ; a : b : c = .9749 : 1 : 

 1.6483 ; P = 89 13' = 001 A 100; 100* 110 = 44 16' ; 001 * 10_1 = 

 58 49'; 001*011 = 58 45'; Common forms, P(lll), e (111), 

 t(101); Twinning plane, 100 ; Cleavage, prismatic distinct ; Brit- 

 tle; Fracture, uneven ; H. = 5-6; G. = 3.06-3.12; Color, azure- 

 blue ; Streak, white ; Subtranslucent to opaque ; a = 1.603 ; 

 P = 1.632; Y = 1.639; Y - a = .036; Optically (-); Axial 

 plane parallel to 010; Bx**c = 9 20'-9 45' behind; 2*E = 

 132 ; Pleochroism strong. 



B.B. Swells, whitens, and crumbles. The powdered mineral 

 moistened with H 2 SO 4 yields a green flame (P 2 O 6 ) or fused with 



