680 MINERALOGY 



c. Insoluble in HC1 or not decomposed. 



. The finely powdered mineral when fused with one 

 and one half parts of soda yields a bead remaining 

 clear when cold. 



OPAL, Si0 2 with water; White, colors of various 

 shades; H. 5.5-6.5; G. 2.15; Amorphous; p. 369. 



/?. Becomes blue with cobalt solution. 



DIASPORE, AIO(OH) ; White, gray, yellowish, green- 

 ish; Cl. pinacoidal; H. 6.5-7; G. 3.40, IV; p. 

 365. 



Zunyite, [A1.2 (OH.F.Cl)] 6 Al 2 (Si.0 4 )3; White, gray; 

 H. 7; G. 2.88; I. 



y. May yield only a very small amount of water. 



STAUROLITE, (AlO) 4 (A1.0H)Fe(S0 4 ) 2 ; Red-brown to 

 brownish black; Cl. pinacoidal; H. 7-7.5; G. 3.65; 

 IV; p. 477. 



IOLITE, H 2 (Mg.Fe) 4 Al 8 SiioO 3 7; Light or dark blue, white; 

 Cl. pinacoidal; H. 7-7.5; G. 2.61; IV; p. 440. 



8. Shows berlium ; p 571. Lavender with cobalt solu- 

 tion. 



Bertrandite, Be2(Be.OH) 2 Si 2 O7 ; White, yellow; Pearly; 

 Cl. prismatic ; H. 6-7 ; G. 2.60 ; IV. 



Euclase, Be(A1.0H)SiO 4 ; White to pale green ; Pearly; 

 Cl. pinacoidal; H. 7.5; G. 3.10; V. 



c. Fused with soda yields a sulphur reaction. 



Melanophlogite, Si0 2 SO 3 H 2 O,etc. ? ; White, light brown ; 



H. 6.5-7 ; G. 2.02 ; I ; Cubes. 

 2. Hardness above 5. 



. Yields no water, 

 a. Soluble or decomposed with HC1. 



a. Fused with potassium flux, shows potassium through 

 the blue glass. 



LEUCITE, KAl(SiO 3 ) 2 ; White, gray; H. 5.5-6: G. 



2.47; I; p. 416. 

 6. Gelatinizes with HC1. 



CHRYSOLITE, (MgFe)Si0 4 ; Olive to grayish green, 

 brown; Cl. pinacoidal; H. 6.5-7; G. 3.33; IV; 

 p. 446. 



. Contains no iron. 



Forsterite, Mg 2 SiO 4 ; White, gray, yellowish ; Cl. pina- 

 coidal; H. 6.5-7; G. 3.24; IV; p. 450. 



