

RE-EXAMINATION OF AMERICAN MINERALS. 125 



distinct composition, and gave it the above name. Its physical 

 characters correspond with rhodochrome and kammererite, but 

 as there had been no analysis published of the first, and as Dr. 

 (xenth's results did not agree with those obtained for kammer- 

 erite, he doubtless felt himself justified in considering it a new 

 species. A short time after his results appeared an analysis 

 of rhodochrome was published by Hermann ; its identity with 

 those of rhodophyllite induced us to re-examine the latter. 

 The results on two analyses are : 



1 2 



Silica 33.26 33.30 



Alumina 10.69 10.50 



Sesquioxide of chromium 4.78 4.67 



Peroxide of iron , 1.96 1.60 



Magnesia 35.93 36.08 



Soda and potash 35 .35 



Water 12.64 13.25 



99.61 99.75 



These will be seen to correspond with the analyses (1, 2) 

 of rhodophyllite by Dr. Grenth, and the analysis of rhodo- 

 chrome (3) and chrome-chlorite (4) by Hermann. 



Si 3tl £e €r Ni Mg Ca Li Na K H 



1. Texas, Pa. 33.41 18.15 trace 35.86 trace 0.28 0.10 12.79 



2. Texas, Pa. 32.98 11.11 1.43 6.85 trace 35.22 trace 0.28 0.10 13.12 



3. L. Itkul... 34.64 10.50 2.00 5.50 35.47 12.03 



4. Texas, Pa. 31.82 15.10 4.06 0.90 0.25 35.24 12.75 



Our analyses give the formula 4E 3 Si+fi 2 Si+IOH. 



Dr. Grenth gives the same formula minus one atom of water. 

 The amount of oxide of chromium varies in different specimens, 

 and to this is due the various shades of color. Dr. Genth in- 

 forms us that he observed a like variation in the specimens he 

 examined. The chrome-chlorite examined by Hermann was 

 undoubtedly one of the light-colored varieties. 



Nickel as well as lime is found in some specimens, but both 

 are impurities. The nickel is due to small particles of sul- 

 phuret of nickel which occur at the same locality, and in 

 many instances are disseminated through this mineral; in 

 some specimens these impurities are not readily detected by 

 the eye. In all probability the carbonate and silicates of nickel 

 found on the Texas chrome iron proceed from the decomposition 

 of this sulphuret. 



