1912] Eakle: The Minerals of Touopah, Nevada 



5 



this zone and some in the lower zone. The embolite is typically 

 deposited in bunches of imperfect crystals on layers of psilo- 

 melane, and the occurrence suggests the possibility that the 

 bromide was soluble in the excess of the. alkali-manganese sul- 

 phates and could not form readily as embolite until some of the 

 sodium and potash was removed with the manganese by evapora- 

 tion. No analyses have been made of the manganese oxides, but 

 doubtless they contain considerable potash and sodium, since 

 these two alkalies were abundant in the solutions. It is well 

 known that the silver haloids are soluble in the alkali chlorides, 

 bromides, and iodides, the alkali carbonates, and probably in the 

 alkali sulphates, so that the general tendency of alkaline solu- 

 tions is to dissolve the silver salts. Cerargerite crystallized in 

 the upper zones because of the predominance of chlorine in 

 dilute solutions of the alkalies, although the solubility of the 

 chloride was raised ; but in the embolite zone the solutions had 

 become more concentrated and at the same time considerably 

 stronger in the alkalies, especially potash from the leaching of 

 the orthoclase, and neither the cerargerite, the iodyrite, nor the 

 embolite of this zone crystallized until the hydrate of manganese 

 was thrown down, carrying the restraining alkalies. 



The solutions percolating downward carried small amounts 

 of chlorine and bromine and most of the iodine in the form of 

 alkali salts of these elements. They also contained large amounts 

 of potassium, iron, and manganese derived from the veins, and 

 in the final evaporation of the waters, abundant coatings of 

 psilomelane, flaky precipitated hematite and platy crystals of 

 jarosite were formed. The wobbly crystals of iodyrite and 

 smaller bunches of embolite are in general perched upon these 

 coatings or crystallized with them, and the evidence seems con- 

 clusive that the iodyrite was soluble in the concentrated solutions 

 and did not crystallize until after the hydrates of iron and of 

 manganese had been precipitated or had begun to form. What 

 kept the iodyrite from forming was probably the strong solu- 

 tions of potassium and sodium sulphates, and it was not until 

 the alkalies had been removed in the formation of the jarosite 

 and psilomelane that the silver iodide could crystallize. Iodyrite 

 is decomposed by strong solutions of potassium or sodium sul- 



