HYALOSIDERITE. Ill 



tions somewhat resembling Fig. 28. and 38., with 

 numerous pyramids and prisms between the six- 

 sided terminal face and the six-sided prism, which 

 has two angles of 129 40' and four of 115 i(X. 

 There occurs frequently regular composition, as 

 in prismatic Lime-haloide, parallel to the faces of 

 a rhombic prism. 



Cleavage, traces parallel to the six-sided face. 

 Fracture imperfect conchoidal. 



Lustre vitreous. Colour various shades of yellow, 

 sometimes almost white, passing into reddish- 

 brown. Transparent ...translucent. 



Brittle. Hardness = 6-5 ... 7'0. 



It occurs on Monte Somma, with mica and various other 

 minerals. Alone before the blowpipe it becomes opake on 

 the outside, but is infusible. It gives a clear glass with 

 borax. 



HYALOSIDERITE. 



Hyalosiderit. WALCHNER. Schweiggers Neues Journal. 

 Vol. IX. p. 65. Edin. Journ. of Science. VoL I. 

 p. 184. 



Prismatic. Combination similar to Fig. 9. Incli- 

 nation of M on M' adjacent, 77 5(X, of P on P', 

 adjacent, 99 22'. 



Cleavage indistinct parallel to h. Fracture small 

 conchoidal. Surface tarnished brass-yellow, or 

 gold-yellow. 



Lustre vitreous, on the surface metallic. Colour 

 reddish- or yellowish-brown. Streak of a cinna- 



