76 PHYSIOGRAPHY. 



Blue Spar. 



BLUE SPAR. Prismatoidal Azure-Spar. 

 MOHS. 



Primary form. Doubly oblique prism ? of unknown di- 

 mensions. 



Cleavage indistinct, sometimes pretty obvious in one di- 

 rection, with traces in other directions, making oblique an- 

 gles with the easily observed cleavage. Massive. Com- 

 position granular, often in large individuals ; strongly co- 

 herent. Fracture uneven, often splintery. 



Lustre vitreous, slightly inclining to pearly upon faces of 

 cleavage. Color smalt-blue, inclining sometimes to white 

 and green. Streak white. Translucent on the edges, of- 

 ten nearly opake. 



Brittle. Hardness = 5-5 ... 6-0. Sp. gr. = 3-024. 



1. Before the blow-pipe it loses its color, but does not melt. It is 

 slowly and with difficulty dissolved in borax. With boracic acid and 

 iron- wire, it yields a globule of phosphuret of iron. 



2. Analysis. 

 By R. BRAITDES. 



Phosphoric acid . . . 43-32 



Silica . . . 6-50 



Alumina . . . 34-50 



Magnesia . . . 13-56 



Lime . . . 0-48 



Protoxide of iron . . . 0-80 



Water . . . 0-50 



3. It occurs in masses, sometimes six or eight inches over; also in 

 large indistinct crystals imbedded in Quartz and mixed with Mica. The 

 rock embracing it, however, has no where been found in place. 



4. It is found in the valley of Freschnitz near Krieglach, on the Mtlrz 

 in Upper Stiria ; also at Therenberg at the foot of the Wechsel mountain 

 in Lower Austria. 



5. The near agreement of Blue Spar with Sodalite in hardness and 

 specific gravity, and the want of certainty in our knowledge respecting 

 the system of crystallization to which Blue Spar belongs, render it pos- 

 sible that the two substances may hereafter be shown to be identical. 



