276 THE JOURNAL OF GEOLOGY. 



It will be seen by the analysis that the ore is an impure 

 oxide of manganese, being possibly a mixture of the peroxide 

 and sesquioxide, though the impurities obscure its true nature. 

 The most remarkable feature of the ore is the considerable 

 amount of tungstic acid present, comprising 2.78 per cent of the 

 ore and corresponding to 2.20 per cent of metallic tungsten. 

 The form in which the tungsten exists in the ore is uncertain. 

 It is possible that it may exist as a tungstate of manganese or 

 iron, or of both, or perhaps of one of the other bases present. It 

 may either have been deposited from solution with the manga- 

 nese, or it may have been brought in as detritus from an outside 

 source during the deposition of the ore, in the same way as the 

 fragments of rock were brought into the deposit. 



Though from a mineralogical standpoint the ore is impure, 

 yet for commercial purposes the analysis shows a good grade of 

 manganese ore, and the presence of the tungsten would give 

 additional value to the ore in the manufacture of certain kinds 

 of hard steel. 



THE NATURE OF THE DEPOSIT. 



The ore occurs as a lenticular deposit imbedded in a soft 

 white or buff colored calcareous tufa which contains fragments 

 of sandstone, shale and massive limestone similar to those found 



^ There is more than a trace of cobalt present but the amount was not determined. 



