440 Larsen and Hicks — Searlesite, a new mineral. 



Analysis and ratios. 







Calculated 









Calculated 





Original 



to 100 









for 





analysis 



per cent 





Eatios 





Na a O.B 2 3 . 

 4Si0 2 .2H 2 



Si0 2 



34-00 



56-41 



•940 



3-72 



4X0-93 



58-82 



B,0, 



9-80 



16-26 



•232 



0-91 



1X0-91 



17*15 



Na 2 



7-70 



12-78 



•2061 







15-20 



K,0 



0-60 



1-00 



•Oil ! 









MgO 



1-10 



1-82 



•045 [ 



1-14 



1X1*14 





FeO 



1*14 



1-89 



•026 J 









A1.0, 



0-22 



0-37 



•004 









H.O 



5-72 

 60-28 



9-47 

 100-00 



•525 



2-08 



2X1'04 



8-83 

 100-00 



The ratios correspond approximately to the following for- 

 mula : Na 2 O.B 2 3 .4Si0 2 .2H 2 0, or Nate(Si0 3 ) 2 .H 2 0, in which 

 a portion of the sodium is replaced by magnesium, iron, and 

 potassium. It seems probable, however, that the iron, mag- 

 nesium, and alumina in the analysis have been derived from 

 the associated gangue as a result of the solvent action of hydro- 

 chloric acid on the chlorite and other silicates known to have 

 been present in the sample, rather than as having been con- 

 stituents of searlesite itself. The presence of the large 

 amount of foreign minerals makes an analysis of purer mate- 

 rial highly desirable, but the optical study has enabled us to 

 correct for calcite and the material insoluble in hydrochloric 

 acid with some confidence. Searlesite differs from most other 

 borosilicates in that it is a derivative of metasilicic acid. Its 

 formula shows a striking analogy to that of analcite : 



Searlesite NaB(SiO,) 2 .H 3 



Analcite _ NaAl(Si0 3 ) 2 .H,0 



