THE MINERALS OF IDAHO 175 



BROMYRITE 



BROMIDE OF SILVER 

 Silver bromide, AgBr. Isometric. 



The remarks given above under embolite apply equally well to the 

 chlorine-free silver bromide, bromyrite, the two minerals being similar 

 in all their properties. While bromyrite probably has been present 

 in some of the rich oxidized silver ores of the State it has not been 

 definitely identified and no specimens have been available for identi- 

 fication. 



IODYRITE (173) 



IODIDE OF SILVER 

 Silver Iodide, Agl. Hexagonal, hemimorphic. 



Like the bromides of silver, silver iodide has occasionally been 

 reported to occur in oxidized silver ores from Idaho, 67 but no speci- 

 mens have been available for examination. The mineral is similar 

 to cerargyrite and bromyrite in general properties and, since it has 

 been found abundantly in Nevada, it probably occurred also in 

 cerargyrite ores in Idaho. 



FLUORITE (175) 



FLUORSPAR 



Calcium fluoride, CaF 2 . Isometric. 



No noteworthy deposits of fluorspar are known in Idaho, the 

 occurrence of this mineral being limited to the ores of a few districts 

 where it forms an unimportant accessory gangue material. 



CUSTER COUNTY 



Fluorite occurs in wide distribution in the Alder Creek or Mackay 

 (White Knob) district in the contact metamorphic copper deposits 

 and in the lime silicate rock near them. Chunks weighing several 

 pounds are present in the dumps from the big quarry of the Empire 

 mine. 670 This is in the form of broad crystalline masses with perfect 

 octahedral cleavage and varying from colorless to faintly purple. It 

 is mixed with some copper silicates. Other specimens are pale 

 purple cleavable masses containing small yellow-green garnet crystals. 

 Fluorite is also common as purple grains in garnet-magnetite rock 

 from 500 feet down the east slope of White Knob and ore from the 

 Tiger claim contains pale green fluorite cleavages associated with 

 bornite and copper silicates in garnet rock. 



Near the head of the North Fork of Lost River fluorite occurs as 

 pale green octahedral crystals up to 1 cm. in diameter in a narrow 



«" J. B. Umpleby. U. S. Qeol. Survey, Prof. Paper 97, p. 53, 1917. 



e:< ■ Reported as identified by W. P. Blake in specimens of ore from the "Boise Region." Oregon Daily 

 Times, Nov. 28, 1864. Capt. John Mnllan, Miners and Travelers Guide, New York, 1865, p. 108. 



