NOTES OX SOME CHILEAN COPPER MINERALS. 



By harry F. KELLER. 



(Read April 24, 1908.) 



Some time ago my brother, Mr. Hermann A. Keller, presented 

 me with a fine suite of mineral specimens collected by him on a pro- 

 fessional trip to Chilean mining localities. The minerals, which in- 

 clude native sulphur and copper, various oxides, chlorides, sulphates, 

 borates and silicates, were for the most part readily identified by 

 their characteristic appearance or by simple tests, but some of them 

 aroused my curiosity, partly because of their rare occurrence, and 

 partly on account of their beauty or exceptional purity. I was thus 

 led to make a number of qualitative and quantitative analyses, the 

 results of which appear to me sufficiently interesting to be placed on 

 record. In the present paper I shall confine myself to the descrip- 

 tion of some minerals containing copper as either a principal or 

 a minor constituent. 



Cupreous Manganese. 

 It is well known that in many varieties of psilomelane or wad the 

 manganous oxide is partially replaced by oxide of copper, and that 

 special names have been given to some of those varieties in which 

 the proportion of the latter oxide is considerable. Among them is 

 the peloconite from Remolinos, Chile, which was first described by 

 Richter,^ and chemically characterized by Kersten.^ Its quantitative 

 composition, however, does not appear to have been fully deter- 

 mined. The material supplied by my brother included several very 

 fine specimens of a cupreous manganese from Huiquintipa, Province 

 of Tarapaca, and these are unquestionably identical with Richter's 

 peloconite. With the one exception of the specific gravity, the 

 physical and chemical characters of the new material are precisely 



^ Poggendorffs Annalcn, 21, 590. 

 ^ Schweigger's Journal, 66, 7. 



PROC. AMER. PHIL. SOC. XLVII. l88 F, PRINTED JULY lO, I908. 



