Larsen and Hicks — Searlesite, a new mineral. 439 



The results of the quantitative analysis are as follows (W. 

 B. Hicks, analyst) : 



Per cent 



Residue insoluble in HC1 __ 11*88 



C0 2 12-84 



Si0 2 34-00 



B 2 3 9-80 



Na 2 _ 7-70 



K 2 0-60 



CaO 12-10 



MgO _. _. 4-20 



FeO* 1-14 



H 2 below 105° C. _ 0-78 



H 2 above 105° C 5-72 



A1 2 3 _ _ 0-22 



CI none 



SO, ___ none 



100-98 

 * The state of oxidation of the iron was not determined. 



Since it has been shown by microscopic examination that the 

 material as analyzed contained large amounts of calcite and 

 considerable quartz, feldspar, and chlorite, w T e are justified in 

 removing these constituents from the analysis before attempt- 

 ing to calculate the formula for searlesite. Since the index of 

 refraction of the carbonate was found to be that of nearly pure 

 calcite (a> = 1*658), all of the calcium has been calculated as 

 carbonate and the excess of carbon dioxide allotted to magne- 

 sium. Determined in this way, the extraneous matter in the 

 sample is as follows : 



Composition of extraneous matter. 



Per cent 



Residue insoluble in HC1 ; 11*88 



CaCO s _ 21-63 



MgCO, 6-41 



HO below 105° C. -_ 0*78 



40*70 



By removing this foreign matter from the analysis, and 

 calculating the remaining constituents to 100 per cent, the 

 following data are obtained : 



