PHYSIOGRAPHY. 229 



Gismondin Glauberite. 



GISMONDIN. Abrazitic Kouphone-Spar. 



Primary form. Right square prism. 



Secondary form. Primary form surmounted by four- 

 sided pyramids, whose faces correspond to the prismatic 

 faces. The adjoining faces of either pyramid incline un- 

 der 122 58' : and a face of the upper pyramid to a cor- 

 responding one of the lower, under 85 40'. 



Cleavage imperfect, parallel to the pyramidal faces. Sur- 

 face, prismatic faces frequently rounded ; the pyramidal 

 ones smooth, and though generally very small, yet possess- 

 ing high degrees of lustre. Fracture conchoidal. 



Lustre adamantine. Color pale smalt-blue, milk-white, 

 pearl-grey and rose-red. Translucent, in small crystals, 

 nearly transparent. 



Hardness =6-0 . . . 6-5. Sp, gr. =2-16 . . . 2-2. 



1. Before the blow-pipe, it phosphoresces, and becomes friable, but is 

 infusible. It gelatinizes with acids without effervescence. 

 2. Analysis. 

 By CARPI. 



. Silica .... 41-4 



Lime .... 48-6 



Alumina .... 2-5 



Magnesia .... 1*5 



Oxide of iron .... 2-5 



3. Gismondin occurs along with white octahedrons of Fluor, Feld- 

 spar and other minerals, in the drusy cavities of a volcanic rock, at Capo 

 di Bove, near Rome. 



It approaches in several of its properties, especially that of form, the 

 species Zircon. 



GLAUBERITE. Prismatic Br i t hy n e-S al t. 



MOHS. 



Primary form. Oblique rhombic prism. M on M'=83 

 20'. Mon P=104 15'. 

 20 



