812 GEOLOGY OF THE ELTKEKA DISTRICT. 



Ricliiuond t'uriuwe for tlie year 1878 was made for the company by Mr. 

 Fre<] Claudet, of Loudon: 



Lead oxide 35-65 Lead 33-12 



Bismuth 



Copper oxide -15 Copper -12 



Iron sesquioxide 34-39 Iron 24-07 



Zinc oxide 2-37 Zinc •. 1-89 



Manganese oxide -13 



Arsenic acid 6-34 Arsenic 4-13 



Antimony -25 Antimony -25 



Sulphuric acid 4-18 Sulphur 1-67 



Chlorine 



Silica 2-95 



Alumina -64 



Lime 1-14 



Magnesia -41 



Water and carbonic acid 10-90 



Silver and gold -10 



99-60 



Silver, 27'55 troy ounces per ton of 2,000 pounds. Gold, 1-59 troy 

 ounces per ton of 2,000 pounds. 



The analysis is taken from the records of the Richmond company. 

 It is reproduced here, as it g'i ves the average composition of a large quantity 

 of ore probably derived from the same ultimate source, and is therefore not 

 without scientific value, although it cannot be considered as representing any 

 definite deposit or the product of any special mode of formation. 



The method of stating the present composition of the ore is somewhat 

 misleading. All the lead is estimated as lead oxide, whereas a very appre- 

 ciable amount of lead sulphide must have been present, as is shown by the 

 examination of any ore pile. It indicates, however, how completely the 

 ore body has undergone oxidation since deposition. No determination was 

 made of the molybdic acid, yet it is hardly possible that none was present 

 when it is easily detected in almost any ore sample. The low percentage of 

 base metals other than lead and iron shows the great uniformity and sim- 

 plicity of the original sulphides. That the ores vary in composition within 

 certain limits, dependei\t upon the position of the ore chamber and tlieir 



