THE ORES. 61 



lesia 41 



Water aud carbonic acid. 10.90 

 Silver and gold 10 



100.52 

 27.55 Troy ounces'" silver per ton of 2,000 pounds. 

 1.59 Troy ounces 6 gold per ton of 2,000 pounds. 



Although this analysis does not show all the substances that are pres- 

 ent in the ores of the Richmond mine, yet it represents the most important 

 and principal ones. One of the remarkable features of this ore is its free- 

 dom from earthy material, the total amount of silica, alumina, lime, and 

 magnesia that it contains being but 5.14 per cent. That it should contain 

 but a small quantity of silica is but natural, as there are no highly silicious 

 rocks immediately connected with it, but that it should carry such a small 

 percentage of lime and magnesia, occurring as it does almost wholly in a 

 limestone formation, is a fact that it is somewhat difficult to account for. 

 Whatever the source of the ore may have been, it is evident that it was 

 deposited almost entirely free from earthy material. The hydrated oxide 

 of iron may be regarded as the gangue of this ore. 



Discussion of the analysis. — Upon examining this analysis it will be noticed that 

 the lead has been estimated in the form of oxide. The lead, however, is 

 present in the form of galena, carbonate, sulphate, molybdate, arsenate, and 

 chloride, the chloride being combined with the arsenate in the mineral 

 mimetite, which is of frequent occurrence in the ore. The mineral pyro- 

 morphite may be present in the ore, but it has not been detected, although 

 there is a trace of phosphoric acid present. Lead is also present in other 

 forms, but as they represent in the aggregate but a small proportion of that 

 metal they may be regarded as merely accessory It is difficult to estimate 

 the proportion of the different lead minerals contained in this ore, but it is 

 probable that galena (sulphide), cerussite (carbonate), and anglesite (sul- 

 phate) are present in about equal quantities, and the next most important 

 combinations are mimetite (arsenate and chloride) and wulfenite (molybdate). 



When copper has been detected in the ore it has been in the form of 

 carbonate. Zinc has been estimated entirely in the state of oxide, but it 



-835.61. '$32.87. 



