E. V. /Shannon — Famatinite from Goldfield, Nevada. 469 



Aet XXXVII. — Famatinite from Goldfield, Nevada; by 

 Earl V. Shannon. 



During last year, through correspondence with Mr. 

 Herbert N. Witt, geologist for Goldfield Consolidated 

 Mining Co., the writer obtained a number of specimens 

 of ore minerals from the Goldfield district, with the idea 

 of investigating the mineral goldfieldite, reported by 

 Ransome^ from that region. With regard to the speci- 

 mens, Mr. Witt writes as follows : 



''I am sending you under separate cover some specimens of 

 the copper ore that occurs here. I believe that you will find 

 that this consists principally of famatinite. However, we have 

 found that almost any specimen of this ore will upon analysis 

 give, not only copper, gold, and sulphur, but arsenic, antimony, 

 bismuth, and tellurium. I do not believe that the mineral gold- 

 fieldite exists but is probably a mixture of famatinite, bismuth- 

 inite, and calaverite or sylvanite, with possibly some tetrahedrite. 

 All of these have been recognized here and the one specimen that 

 I have had in polished surface under the reflecting microscope 

 indicates such a mixture. . . . You may be able to detect 

 some of the whitish telluride in the famatinite specimens. This 

 will then, I believe, give you all the constituents of the so-called 

 'goldfieldite'." 



One of the specimens had, on one side, some very 

 minute crystals, of a blackish-gray color and metallic 

 luster, partly embedded in kaolin. These were carefully 

 tested in the hope that they might be goldfieldite but 

 although strong reactions were obtained for antimony, 

 arsenic, copper, and sulphur, no bismuth or tellurium 

 could be detected in the very small amount of material 

 available. The crystals therefore seem to be of the same 

 substance as the main mass of the specimen on which 

 they occur, an arsenical famatinite. The crystals vary 

 in greatest diameter from about 1 mm. doT^m to about 

 0.1 mm., and are so attached to the matrix that they could 

 not be detached without breaking. The larger crystals 

 furthermore had curved faces which gave no dependable 

 reflections. After repeated trials a small crystal was 

 found giving moderately good reflections. In the litera- 

 ture at hand no axial ratios are given for famatinite. 

 Dana^ gives the forms observed by Rath, as a (100), 

 c(OOl), m(110) and ^(130), but gives no axial ratios, nor 

 does he give any angles. Rath's original paper is not 

 accessible to the writer, hence the angles found on the 



^ Eansome, F. L., TJ. S. G. S., Prof. Paper, No. 66, 1909. 

 ^ System of Mineralogy, 6th ed., page 149. 



