138 RE-EXAMINATION OF AMERICAN MINERALS. 



varieties, and for that reason the examination was made. The 

 specific gravity was 3.122. Two analyses gave 



Oxygen. Oxygen. 



Phosphoric acid 43.38=24.31 44.15=24.74 



Alumina 31.22 14.59 32.17 15.03 



Protoxide of iron 8.29 1.84 ^ ^ o« 8.05 1.79 1 r fin 



Magnesia 10.06 4.02 / °- 0D 10.02 4.01 / °' 8U 



Water 5.68 5.05 5.50 4.89 



Si 107 1.07 



99.70 100.96 



No. 1 has the oxygen ratio=24.90 : 14.94 : 6 : 5.16, or very 

 nearly 25 : 15 : 6 : 5. No. 2 has=25.56 : 15.54 : 6 : 5.04. From 

 these we deduce the formula 



2 (Mg, Fe) 3 P+£l 5 P 3 +5H. 



Atoms. At. weight. Per cent. 



Phosphoric acid 5 4460 44.02 



Alumina 5 3209 31.67 



Protoxide of iron 2 900 8.88 



Magnesia 4 1000 9.87 



Water 5 563 5.56 



The formula differs from that of Bammelsberg by one atom 

 less of alumina and of water; calculated by his formula, it 

 would give the alumina much too high for our analyses. The 

 phosphoric acid was separated from the alumina by fusing the 

 mineral with carbonate of soda and silica, this being the most 

 perfect method, in fact the only one to be safely relied on. It 

 appears to be identical in specific gravity and composition with 

 the variety from G-ratz examined by Eammelsberg. 



33. Kyanite. 



Associated with the lazulite just described is a very beau- 

 tiful white kyanite. Its composition is 



Silica 37.60 



Alumina 60.40 



Peroxide of iron 1.60 



99.60 

 This corresponds to the formula £l 3 §i*= silica 37.47, alumina 

 62.53. 



34. El^olite. 



The elseolite of Magnet-cove in Arkansas passed under the 

 name of " flesh-red feldspar " until recognized by Prof. Shepard.* 

 It has the following physical and chemical properties : Hard- 



* Amer. Jour. Science and Arts, 2d series, ii, 252. 



