of 



Constituents of various Minerals. 257 



By the analysis of Mr THOMAS Mum, Nutallite is composed 



Silica, . ;'V ' . . . 37.808 



Alumina, '. ": . . . 25.104 



Lime, 18.336 



Protoxide of iron, . , 7.892 



Potash, 7.305 



Water, 1.500 



97.945 



Were we to consider these constituents as all essential to the 

 chemical constitution of the mineral, it would consist of 



that is to say, of 



3 atoms silica of alumina. 



1 atom of a triple silicate of lime, peroxide of iron and pot- 

 ash, in the proportions given in the formula : viz. 



4 atoms silicate of lime. 



1 atom persilicate of iron. 

 1 atom silicate of potash. 



* 



But whether any of these (and how many) be not accidental in- 

 gredients, can only be determined when we have an opportunity 

 of analysing Nutallite from other localities. 



9. Pipestone. 



I give this name to a mineral from North America, which the 

 Indians use for making tobacco-pipes. The specimen in my pos- 



