S. L. Penfielcl — Canfieldite, a new Germanium Mineral. 113 



Freiberg argyrodite in the collection of Prof. Brush. The 

 specific gravity was determined in two ways. Some larger 

 fragments, weighing abont two grams, gave on the chemical 

 balance in distilled water 6-149 and the smaller ones gave by 

 use of the pycnometer 6*162. These results, though some- 

 what higher than those given by Winkler and Weisbach, 

 which were 6-0S5-6-111, are still considerably lower than the 

 specific gravity of canfieldite. The result of the analysis is 

 as follows : 









Average. 



s__ 



.. 16-97 





16*97 



Ge 



_. 6'67 



6-62 



6-64 



Ag 



._ 7557 



7553 



75*55 



Hg .... 



•34 





•34 



Fe, Zn.._ 



•24 





•24 



99-74 



It will be seen that this analysis agrees remarkably well 

 with that of Winkler, the only essential difference being that 

 the silver is somewhat higher and the iron and zinc are lower. 

 This suggests that these latter are impurities, resulting from 

 the presence of a slight admixture of pyrite and sphalerite, 

 both of which are associated with the mineral. In regard to 

 the mercury, since this element has never been known to occur 

 otherwise at Freiberg, it is probable that it replaces silver. If 

 we now recalculate these analyses, excluding the iron and zinc 

 with sufficient sulphur to form pyrite and sphalerite, and re- 

 placing the mercury by its equivalent in silver, we obtain the 



following : 









Canfieldite. 



Argyrodite, 

 Winkler. 



Argyrodite, 

 Author. 



Theory for 

 Ag 8 GeS 6 



17-10 



16-56 



16-S3 



17-06 



6'57 



7-05 



6-69 



6-42 



76-33 



76-39 



76-48 



76-52 



100-00 100-00 100-00 100-00 



From the consideration of these results there can be no 

 doubt that canfieldite and argyrodite have the same chemical 

 composition, which is Ag 8 GeS 6 . It is evident therefore that 

 we have here a case of dimorphism, for both the crystalline 

 forms and the specific gravities indicate that the minerals are 

 distinct. 



Laboratory of Mineralogy and Petrography, 

 Sheffield Scientific School, June, 189H. 



Am. Jour. Sci.— Third Series, Vol. XLYI, No. 272.— August, 1803, 

 8 



