PHYSIOGRAPHY. 163 



Red Zinc-Ore. 



RED ZINC-ORE. Hemi-prismatic Eruthrone- 

 Ore. 



Primary form. Right rhombic prism ? 



Cleavage, in one direction perfect, in three others less 

 so, and apparently different in each. Two angles are af- 

 forded by the reflective goniometer, one of 125, the oth- 

 er of 90. Fracture conchoidal. 



Lustre adamantine. Color red, inclining to yellow. 

 Streak, orange-yellow. Translucent on the edges. 



Brittle. Hardness =4-0 ... 4-5. Sp. gr. =5-432... 

 5-523. 



Compound Varieties. Massive ; composition granular, 

 individuals strongly connected. 



1. On exposure to the air, it suffers partial decomposition at the sur- 

 face, becoming invested with a while coating, which is carbonate of 

 zinc. Alone before the blow-pipe, it is infusible, but yields a yellow 

 transparent glass with borax. It is soluble without effervescence, in 

 nitric acid. 



2. .Analysis. 



By BRUCE. By BERTHIER. 



Oxide of zinc . . . 9200 . . . 88-00 

 Oxide of iron and manganese 8-00 . . . 12-00 



3. It occurs massive, mixed with Calcareous Spar and Franklinite, at 

 Franklin and Stirling, (N. J.) It is set free in several metallurgic pro- 

 cesses, and occurs crystallized in six-sided prisms of a yellow color, in 

 the foundaries of Konigshiltte in Silesia. 



RETINASPHALT. (See Retinite.) 



RETINITE. 



Roundish, and blunt-edged masses. Fracture conchoidal. 



Lustre resinous. Color green, yellow, red, brown, sometimes 

 in striped delineations. Semi-transparent to opake. 

 Hardness =1-5 . . . 2-0, of the variety from Halle. Sp. gr. = 

 1-135. 



