80 



PHYSIOGRAPHY. 



Boracite Borax. 



Lustre vitreous, inclining to adamantine. Color white, 

 inclining to grey, yellow and green. Streak white. Semi- 

 transparent, translucent. 



Hardness =7'0. Sp. gr. = 2*974 of an isolated crystal. 



1. Before the blow-pipe, on charcoal, it intumesces, and melts into a 

 glassy globule, which becomes white and opake on cooling. It is elec- 

 tric by heat, four alternating terminal points of its cubic axes being 

 positive, and those which are opposite to them, negative. 

 2. Analysis. 

 By PFAFF. 



Boracic acid .... 54-55 



Magnesia .... 3O68 



Oxide of iron . . . . 57 



Silica .... 2-27 



3. Boracite is found in remarkably distinct crystals, about the size of a 

 pea and under, imbedded in compound varieties of Gypsum, and rarely 

 in Anhydrite. 



4. The only known localities are Ltineberg in Brunswick and Sege- 

 berg in Holstein. 



BORAX. Prismatic Borax-Salt. MOHS. 



Primary form. Oblique rhombic prism. M on M' 93 

 30'. 



Secondary form. 



P on M or M' 

 M or M' on h 

 Mon& 

 Mone 

 P on A 

 P ongl 

 P on g2 

 P on e 

 e on 0-2 



101 30 



133 20 



136 



138 



106 



139 



115 



114 



141 



Fig. 72. 



45 

 12 

 30 

 15 

 30 

 28 

 52 



