136 RE-EXAMINATION OF AMERICAN MINERALS. 



1 2 



Silica 45.60 48.89 



Alumina 4.87 7.23 



Oxide of iron 2.09 2.46 



Manganese trace trace 



Lime 1.07 



Magnesia 24.10 24.17 



45 .81 



Soda, 1 

 Potash, / 



Water 20.66 15.66 



98.84 99.22 



The specimen No. 1, as already stated, came directly from 

 Dr. Owen ; No. 2 from Dr. Genth. The original analysis of Dr. 

 Owen, with the exception of the new earth, does not differ very 

 materially from the above, when we consider that the saponites 

 vary more or less in their composition. It is as follows : 

 Si 3tl Fe new earth Mg K Mn H 



42 4.6 1.5 10-12 20.5 0.8 trace 18 



If then the existence of a new earth in this mineral can not 

 be established, it is clear that it must be a saponite, with which 

 mineral it is identical in physical properties. 



30. Hudsonite, a Pyroxene. 



This species was described by Prof. L. C. Beck * It has 

 since been shown to be a pyroxene in which a portion of the 

 silica is replaced by alumina. Beck and Brewer obtained for 

 its composition 



Si 2tl Fe Mn Mg Ca 



36.94 11.22 36.03 2.24 12.71= 99.14. Brewer.f 



37.90 12.70 36.80 1.92 11.40 = 100.72. Beck. 



A recent examination of some specimens has shown the 

 presence of a considerable amount of alkalies. The mineral 

 was received from Mr. Silas R. Horton, and is the same as was 

 sent by him to Prof. Beck. The results of two analyses are 



1 2 



Silica 39.30 38.58 



Alumina 9.78 11.05 



Protoxide of iron 30.40 30.57 



Protoxide of manganese .67 .52 



Lime 10.39 10.32 



Magnesia 2.98 3.02 



Potash 2.48) 41R 



Soda 1.66/ ' 



Ignition 1.95 1.95 



99.61 100.17 



* Mineralogy of New York, p. 310. 

 f From Dana's Mineralogy, 3d edition, p. 267. 



