364: W. IT. Hobbs — Goldschmidtite, a New Mineral. 



of its constituent elements, can be discovered, as has been done 

 in the case of the minerals of the humite group. 



Goldschmidtite 

 Au 2 AgTe e 



Monoclinic 

 fi= 89° 11' 



a : b : c 

 1-8562 : 1 : 1-2981 



Perfect cleavage (010) 

 Common twinning plane (100) 

 Columnar axis, c 



Sylvanite 

 AuAgTe 4 . 



Monoclinic 

 j3 = 89° 35' 



a : b : c 

 1-6339 : 1 : 1*1265 



Perfect cleavage (010) 

 Common twinning plane (101) 

 Columnar axis parallel to (101) 





Angles. 



An 



£les. 



Diffi, 



a : m 



61°41' 



58° 



32' 



+ 3° 9' 



b : m 



28 18 



31 



28 



— 3 10 



f : « 



42 42 



39 



15 



+ 3 27 



s : a 



54 57 



54 



57 





S : a 



55 35 



54 



52 



+ 43 



n : a 



34 13 



35 



48 



— 1 35 



n : s 



20 43 



19 



9 



+ 1 34 



a : N 



34 58 



35 



16 



— 18 



c : a 



89 25 



89 



35 



— 10 



S : N 



20 37 

 Conch 



19 

 sions. 



36 



+ 1 1 



1. Goldschmidtite is a new mineral species of composition 

 represented by the formula Au 2 AgTe 6 . 



2. It occupies an intermediate position exactly half way 

 between calaverite and sylvanite. 



3. Calaverite, Goldschmidtite, and sylvanite form together 

 an homologous series, analogous to that of the- minerals in the 

 humite group, the common difference being the addition of 

 Ag 2 Te and the subtraction of Auf in passing from any one of 

 the series to the next above it. 



4. Goldschmidtite has monoclinic symmetry with ft 89° IT, 

 and a : b : c, 1*8562 : 1 : 1-2981. It exhibits no less than 

 twenty-two crystal forms, most of which are in the zones of 

 6 and b. 



5. Crystallographically as well as chemically Goldschmidtite 

 shows affinities with sylvanite, ten forms being common to the 

 two minerals, though they are referred to axial unities of 

 which a and 6 are each about one-seventh longer in Gold- 

 schmidtite than in sylvanite. 



University of Wisconsin. 



