PHYSIOGRAPHY. 287 



Jamesonite. 



3. Its localities are numerous ; the principal ones, however, are the 

 banks of the Mersey near Liverpool, England, and Iserweise in the Rie- 

 sengebirge. 



4. Iserine possesses a strong affinity to Crichtonite in its most impor- 

 tant properties, with which it is probable that future researches will 

 prove it identical. 



IsOPYRE. 



Regular forms not observed. Massive, in very pure masses of 

 considerable size, (nearly two inches in each direction) : compo- 

 sition impalpable. Fracture conchoidal. 



Lustre vitreous, often considerable. Color greyish black and 

 velvet, occasionally dotted with red. Streak pale greenish grey. 

 Opake, or very faintly translucent on the thinnest edges, with a 

 dark, liver brown tint. 



Brittle. Hardness = 5-5 .. .0-0 Sp.gr. = 2-91. 



Slight action on the magnetic needle. 



1. From the description of Tachylite, (by BREITHATJFT,) it would 

 seem that Isopyre is identical with that substance, excepting that the sp. 

 gr. of Tachylite is only 2 5 ... 2 54. 



2. Before the blow-pipe, it fuses without the disengagement of moist- 

 ure or gas; melted in salt of phosphorus, it gives indications of silica. 



2. Analysis. 

 By TURNER. 



Silica .... 47-09 



Alumina .... 13-91 



Peroxide of iron - 20-07 



Lime .... 15-43 



Peroxide of copper - - - 1-94 



4. Isopyre is found in the west of Cornwall. 



ITTNERITE. (See Sodalite.) 

 JADE. (See Nephrite.) 

 JAMESONITE. Axotomous Antimony-Glance. 



MOHS. 



Primary form. Right rhombic prism. M on M= 101 

 )20'. 



