200 PHYSIOGRAPHY. 



Sphene. 



Cleavage sometimes distinct in the direction of d : tra- 

 ces parallel with M. Fracture imperfectly conchoidal, un- 

 even. Surface, b and M almost always faintly streaked, par- 

 allel to the edges of combination with d. The remaining 

 faces are mostly smooth, and often possess high degrees of 

 lustre. 



Lustre adamantine, sometimes inclining to resinous. 

 Color brown, yellow, grey, green ; they are not lively, some 

 pistachio-green ones excepted. Streak white. Translu- 

 cent . . . translucent on the edges. 



Hardness =5*0 . . . 5-5. Sp. gr. =3*468, of a massive 

 yellowish grey variety from Norway. 



Compound Varieties. Twin-crystals : faces of compo- 

 sition parallel, axis of revolution perpendicular to c; some- 

 times the individuals are continued beyond the faceofecJm- 

 position. Massive : composition granular or lamellar, the 

 first are strongly connected. 



1. Before the blow-pipe, the yellow varieties do not change their col- 

 or; all the rest become yellow. They intumesce a little* and melt on 

 the edges into a dark colored enamel. They are soluble in heated nitric 

 acid, leaving behind a siliceous residue. 



2. Analysis. 



By KLAPROTH. By CORDIER. 



Lime . . 33-00 . . . 3220 



Oxide of titanium . 33-00 . . . 33 30 

 Silica . . 35-00 . . . 28-00 



Oxide of manganese . a trace . . . 0-00 



3. Sphene occurs in small nodules or crystals imbedded in gneiss and 

 beds of sienite and other trap rocks, belonging to them, or to more re- 

 cent classes of mountains. It is met with in metalliferous beds with ores 

 of iron, several species of Augite Spar and Feldspar: likewise in beds of 

 primitive limestone, and in veins which traverse primitive rocks. 



4. It occurs in several districts of the Saualpe in Carinthia, imbedded 

 in coarse grained gneiss; at Hafnerzell in the district of Passau, it occurs. 



