JKFFERSOXITE. 115 



IflON-SINTEB. 



Iron-Sin ier. JAM. Syst. Vol. III. p. 250. 

 Reniform, stalactitic ... massive. Composition im- 

 palpable. Fracture conchoidal. 

 Lustre vitreous. Colour yellowish-, reddish-, black- 

 ish-brown. Transparent ... translucent on the 

 edges. 

 Not very brittle. Soft. Sp. Gr. = 2-40, KAB STEN. 



Before the blowpipe it intumesces, and some varieties 

 emit a strong arsenical odour, during which they are partly 

 volatilised. It consists, according to KLAPROTH and S T RO- 

 ME YEK, of 



Oxide of Iron 67'00 33-46. 



Arsenic Acid 0-00 26-06. 



Sulphuric Acid 8-00 10-75. 



Protoxide of Manganese 0-00 0-59. 



Water 25-00 28-48. 



It is found in several old mines, as at Freiberg and 

 Schneeberg in Saxony, and in Upper Silesia. 



JEFFERSONITE. 



AUGITE-SPAR. 



Jeffersonite (Polystomous Augite-Spar). KEATING. Journ. 

 Acad. Nat. Sciences, Philadelphia. Vol. II. p. 194. Edinb. 

 Phil. Journ. VoL VII. p. 317. Jeffersonite. PHILL. 

 p. 24. 



Herni-prismatic. Massive. Cleavage, P -f- oo = 

 106 ; also P oo, inclined at angles of 94 45' 

 and 85 15' to the axis, less perfect than the for- 

 mer ; besides these, also other faces occur, which 

 are parallel to the axis, and intersect each other 

 at angles of 116 and 64, and of 99 45' and 

 80 15', according to KEATING. Fracture uneven. 



