RE-EXAMINATION OF AMERICAN MINERALS. 



145 



position ensues, with a deposition of the oxide of iron and the 

 formation of a soluble sulphate. On analysis it" afforded 



1 



Sulphuric acid 30.25 



Peroxide of iron 31.75 



Water 38.20 \ 



Undissolved 54 / 



2 



30.42 



30.98 



not estimated. 



100.74 



The analyses correspond to the formula FeS 2 +HH. This is 

 the same formula as that obtained by Eose, with an additional 

 half atom of water, his formula being 23?eS 2 +21H. Protoxide 

 of iron was looked for, but none found. 



40. OWENITE,* IDENTICAL WITH THURINGITE WITH AN AN- 

 NOUNCEMENT of a New Locality. 



Owenite was first described by Dr. F. A. G-enth as a distinct 

 species, who gave a minute and accurate analysis in the Amer- 

 ican Journal of Science and Arts, vol. xvi, 2d series, page 167. 

 It was found on both sides of the Potomac Eiver, near Har- 

 per's Ferry. The physical characters being already fully and 

 accurately given, it is needless to repeat them here, merely 

 remarking that its specific gravity as taken by me is 3.191. 

 It is readily soluble in hydrochloric acid; notwithstanding, 

 analysis No. 2 was made by fusion with carbonate of soda. 



Eesults of analyses as follows : 



i 



Silica 23.58 



Peroxide of iron 14.33 



Alumina 16.85 



Protoxide of iron 33.20 



Protoxide of manganese.. .09 



Magnesia 1.52 



Lime 



Soda 46 



Potash trace 



Water 10.45 



2 



Genth. 



23.52 



23.21 





13.89 



16.08 



15.59 



32.18 



34.58 





trace 



1.68 



1.26 





.36 



« 



.41 





.08 



10.48 



10.59 



100.50 99.97 



After this examination it was rendered strongly, probable 



that owenite and thuringite were similar if not identical 



minerals, yet in the analysis of thuringite by Eammelsberg 



alumina is not mentioned as one of its constituents. This 



• The identity of these two minerals had already heen announced by me 

 in a letter to one of the editors of the Amer. Jour. Science and Arts, xvii, 

 131, but no details were then given. 



