PHYSIOGRAPHY. 229 



Tephroite. 



tion.* Massive*, composition granular . . . impalpable. Fracture 

 uneven. 



1. Before the blow-pipe, it decrepitates a little, and burns with a blue 

 flame, emitting copious arsenical vapors, and melting at last into a black 

 scoria, which affects the magnetic needle. 

 2. Analysis. 

 By R. PHILLIPS. 

 Copper 45-32 



Arsenic 11-84 



Iron 9-26 



Sulphur 28-74 



Silica 5-00 



3. It occurs in several of the Cornish copper mines, in veins travers- 

 ing granite and clay-slate ; and is accompanied by several ores of copper. 



4. It is probable that Tennantite, which was formerly included under 

 Fahlerz, will prove to be a distinct species. Its inferior specific gravity, 

 and greater hardness, are favorable to this idea. 



TEPHROITE. 



Massive : composition granular, of various sizes of individuals. 



Cleavage, parallel with the sides of a prism, but indistinct ; with 

 the faces of an octahedron, only in traces. Fracture even to sub- 

 conchoidal. 



Lustre adamantine. Color ash-grey, dark liver-brown to black. 

 Streak pale ash-grey. 



Hardness =5-00. Sp. gr. = 4-104 .. .4-116. 



1. Fusible before the blow-pipe into a black scoria. 



2. Its locality is given as Sparta, (N.J.) where it is said to occur along 

 with Franklinite. 



3. It appears to be a variety of Troostite. 



TESS ELITE. - (See Apophyllite.) 

 TESSERAL-PYRITES. 



Massive. Cleavage, parallel with the faces of a cube, distinct ; 

 with the faces of the dodecahedron only in traces. 



* The existence of the regular composition is most easily ascertained 

 by the strise upon the faces of the cube, which are parallel to the edges 

 of combination with one of the tetrahedrons. 



VOL. II. 20 



