308 IRVING. 



Blue Ore. 



Silica 68.748% 



Alumina ■. . . 3.072 



Iron 1.3-289 



Sulphur ... 11.728 



Gypsum 0.833 



Fluorite . 0.784 



Phosphorus pentoxide 0.842 



Tellurium 4.03 oz. per ton 

 Gold 0.325 oz. per ton 



Silver 10.55 oz. per ton 



Total 99.296 



" These may be considered as low-grade ores, and it is interesting to note that 

 the analysis of the red ore might be almost duplicated by that of the blue ore, after 

 oxidation, during which the latter might be expected to lose iron and sulphur. 



" Taking averages of the tellurium, gold and silver found in the analysis of nine 

 different samples of Potsdam ore, six being 'red' and three being 'blue,' the fol- 

 lowing percentages were obtained : 



"Tellurium 59-97% 



Gold 7.64 



Silver . 32.39 



Total 100.00" 



Much discussion has taken place over the form in which the 

 gold exists in these ores. Little or no free gold ever occurs in 

 them, and the only mineral which would contain the gold is 

 the pyrite, which can always be detected in considerable quan- 

 tities in the unoxidized varieties. Since the publication of the 

 paper above quoted. Professor Smith informs me that spectro- 

 scopic investigation has revealed the presence of considerable 

 thallium in the ores. 



The value of the ores varies within wide limits, running any- 

 where between ^6.00 and $60.00 per ton, and, in some in- 

 stances, even higher. The average yield is, however, from 

 ;^ 1 5.00 to ^20.00 per ton. Owing to the expense of treatment, 

 ores below ^lO.oo per ton have not yet been mined at a profit. 



Origin of the Ores. — The nature of the ore bodies and the 

 character of the ores will at once make it manifest, that they are 

 to be regarded as chemical replacements of the calcareous 



