ORES AND VEIN MATERIALS. 



607 



1 and 2 (especially tlie latter) show that the chief constitueut in these cases is probably 

 jaronite, K2S04+(Fe2)S30,2+2H6(Fe2)06. As there remains a slight excess of SO3 and 

 Fe^Os after combining the constituents of this mineral on the basis of the alkalies 

 present, a basic ferric snlphate is to be assumed as a further cousiitnent of the mixture. 



Analysis 3 shows little pyromorphite, much anglesite, little jarosite, and much 

 hydrated basic ferric sulphate, of which latter it is impossible to determine the formula 

 definitely, since it is not known how much ferric oxide and water maybe combined 

 with the arsenic pentoxide. 



The remaining partial analyses were made to ascertain whether or not the alkalies 

 were constant constituents of this class of products of alteration of the original vein 

 material. Qualitative tests showed that pyromorphite and anglesite were occasionally 

 present in greater amount than shown in analyses 1, 2, and 3. Arsenic pentoxide was 

 found in very considerable quantity in the material from the Silver Cord mine (7). 



Table XIII. — Miacellaneous alteratiov products. 



aCoDsiflte of calciam carbonate, with a little majpiesiam ami less manganese carbonate. 



b Specific gravity at ISJ® C. = 2.570. Hardness, 6. 



c Soluble in stronf; solution of potassium hydrate after four to five hours' di^eation = 65.73 per cent- 



d Specific gravity at 16^'' C. = 2.023. Hardness 5.5. 



e Soluble in strong solution of potassium hydrate after four to five hours' digestion = 97.42. 



