478 



PALACHE AND SCHALLERI HODGKINSONITE 



following results. Quarter gram samples were used as the total 

 amount of available material was only somewhat over a gram. 



Analysis and Ratios of Hodgkinsonite (by W. T. Schaller) 



* A duplicate determination of ZnO, of which a small amount was lost, gave 

 51.38 per cent. 



t Determined directly by fusing the mineral with sodium carbonate and col- 

 lecting the water in a calcium chloride tube. A determination of the loss on 

 ignition, corrected for oxidation of the manganese, gave the value 4.68 per cent. 



A doubtful trace of lead was encountered but iron and chlorine 

 were absent. No water was given off by the mineral at 110°. 



The ratios yield sharply the formula 3 RO.SiO2.H2O where 

 R is chiefly zinc and manganese. If the manganese, calcium 

 and magnesium be arbitrarily taken together then the ratio of 

 MnO + CaO + MgO to ZnO is 309 to 653 or 1 : 2.11 or nearly 

 1 : 2. The formula may then be written MnO.2ZnO.SiO2.H26 

 which may, as the water is all constitutional, be interpreted as 

 Mn.(ZnOH)2.Si04. 



