PHYSIOGRAPHY. 



Allophane Alum. 



ALLOPHANE. Uncleavable Wa velline-Spar 



Reniform, botryoidal, massive ; composition impalpable. 



Fracture conchoidal. 



Lustre vitreous, inclining to resinous. Color blue, green, 

 brown and grey. Transparent . . . translucent on the edges. 



Hardness = 3-0 nearly. Sp. gr. = 1 -85 ... 1-88. 



1. Alone upon charcoal before the blow-pipe, it does not melt, though 

 it swells up, becomes feebly coherent, and communicates to the flame a 

 copper green color. With borax, it fuses with great difficulty into a col- 

 orless glass. It is not soluble in soda ; but the mass becomes green in 

 the oxidation heat, and red in the reduction flame : on the addition of bo- 

 rax, a speck of metallic copper may be obtained. 

 2. Analysis. 



3. It is found at Saalfeld in Thuringia, Schneeberg in Saxony, and at 

 Taune in the Hartz. 



ALMANDIN. (See Garnet.) 

 ALUM. Octahedral Alum-Salt. MOHS. 



Stalactitic : composition columnar or granular, often im- 

 palpable. Mealy efflorescence. 



Lustre vitreous ; if delicately fibrous, pearly ; sometimes 

 dull. Color white or greyish white. Transparent . . . 

 translucent or opake. 



Hardness=2-0 . . . 2-5. Sp. gr.= l-75. Taste sweet- 

 ish astringent. 



