434 Hillebrand — Emmonsite (?) from a New Locality. 



Te0 2 _.. 70-83 



Fe 2 3 22-67 



H 2 Oatl00° ) 4 . 6g 

 H 2 above 100° f 



P,0, -- 0-34 



Al.O. 



Si0 2 , etc.* 







Mean. 



Eatios. 



71*80 



70-20 



70*71 



3-16 



22-81 



22-79 



22-76 



1-00 



4-82 



0-21 



0-21 









4-54 



1-77 







0-34 





0-58 



054 



0-56 



0-88 





100-00 



Allowing alumina to offset the P a 6 , though it may belong to 

 a soluble silicate or to the tellurite and a small proportion of 

 iron be demanded for the P 2 G 5 , the ratios given in the final 

 column result. They are as unsatisfactory as those afforded by 

 the original emmonsite, which were for Fe 2 G 3 : Te0 2 , 1 : 3*65 in 

 the original description and 1 : 3-75 : 1-82 for Fe 2 3 : Te0 2 : H 2 

 if the supplementary determinations in this Journal, xl, 81, 

 1899, are accepted. The presence of tellurite in association 

 with the green mineral suggests a possible explanation of the 

 failure to obtain a simple ratio, though such contamination was 

 not noted in the material analyzed nor on the neighboring 

 gangue. If this explanation is correct, however, the variation 

 from the original emmonsite ratio becomes still more marked. 

 Provisionally the mineral may be regarded as emmonsite. 



The above results are given in some detail, notwithstanding 

 their inconclusiveness, because of the importance of accumula- 

 ting data regarding the as yet small but interesting group of 

 ferric tellurites, and inciting collectors and mining men to care- 

 ful search for and preservation of further material for more 

 extended study. 



Thus far, emmonsite, durdenite, and an unnamed mineral 

 from Cripple Creek, described by Knight in the Proc. Colorado 

 Sci. Soc, v, 66, and affording likewise unsatisfactory ratios, 

 comprise the list of natural ferric tellurites, the formula of 

 no one of which can be regarded as established beyond ques- 

 tion. 

 U. S. Geological Survey, Washington, D. C, Oct. 1904. 



* Includes alkalies, traces of magnesia and gold, and a small amount of a 

 metal or metals precipitable by hydrogen sulphide, whose identity could not be 

 established. 



