230 W. F. Blake — Iodobromite in Arizona. 



Art. XIX. — Iodobromite in Arizona; by William P. 



Blake. 



The rare compound of silver, iodine, bromine and chlorine, 

 iodobromite, occurs in thin seams and crusts in a vein of quartz 

 and calcite near Globe, Final County, Arizona. The crystalli- 

 zation is obscure. It is soft like talc ; luster vitreous ; color 

 light lemon-yellow to sulphur- and canary -yellow. Not being 

 able to secure enough for a satisfactory quantitative analysis, 

 the results of the determinative tests are added. The reactions 

 before the blowpipe are remarkably beautiful and interesting. 

 Heated in a closed tube with bisulphate of potash, the min- 

 eral quickly changes color to a dark salmon, or orange-red, 

 heavy brownish-red fumes of bromine are given off and bro- 

 mine condenses in the higher portion of the tube ; violet vapor 

 of iodine then appears and crystals of iodine form below the 

 condensed bromine. The fused assay, floating in the flux, is 

 brilliant cherry red, at first very dark red, but on cooling grad- 

 ually loses this color, passing through various shades of red 

 until the normal yellow color is restored. The fused mass then 

 being removed from the tube and reheated until the bromine 

 and iodine are expelled, and treated with carbonate of soda on 

 charcoal, a button of metallic silver is obtained. The fused 

 carbonate of soda dissolved from the coal gives the reaction 

 for chlorine with silver nitrate. In the final reduction of the 

 assay to the metal a slight yellow areola like that from lead 

 was observed and referred to probable slight impurity. 



Arizona School of Mines, Tucson, Arizona. 



