360 W. H. Hobbs — Goldschmidtite, a New Mineral. 



Analyses of Calaverite. 



Te Au Ag Total 



1. California, Genth* 55:89 40-70 3-52 100-11 



2- " " f (56-00). 40-92 3'08 lOO'OO 



3. Bowlder Co., Colo. Gently 5l'6l 40-59 2-24 100-50 



4. « « " § 57-32 38-75 3'03 99*10 



5. Cripple Creek, Colo. Hillebrand||._ 57*60 39-17 3-23 1.00-00 



6. " " " 1-- 57-40 40-83 1'77 ' 100*00 



7. « « " **__ 57-30 41-80 -90 100-00 



Calaverite of formula Au 9 Ag|Te 31 ... 57'40 39-08 3-52 100-00 



Comparison of the minerals calaverite, G-oldschmidtite, and 

 sylvanite brings out the fact that Goldschmidtite is, as regards 

 its composition, intermediate between calaverite and sylvanite 

 and almost exactly half way between them. Together the 

 three minerals represent an homologous series quite analogous 

 to that which has been determined for the minerals of the 

 humite group by Penfield and Ho we. ft This will be clear 

 from the following table : 



Te Au Ag 



Per cent. Ratio. Per cent. Ratio. Per cent. Ratio. 



Calaverite 57*40 -4544 39-08 -1987 3'52 *0327 



Au 9 Ag|Te 01 ... (21 = -4536) (-?/ = -1944) (| = *0363) 



Difference" 2*55 *0256 7*54 *0388 5*09 *0473 



Goldschmidtite 59*95 *4800 31'44 -1600 8*61 *0800 



Au 2 AgTe 6 (22 = *4752) (*£■ = -1584) (^=-0799) 



Difference 2*20 *Ol76 699 *0336 4*79 *0444 



Sylvanite 62*15 *4976 24*45 *1244 1340 -1244 



AuAgTe 4 (23 = -4968) (-*/ = -1235) (^=-1235) 



From the above table it is seen that the common difference 

 between consecutive members of the series in ascending order 

 is a gain of Ag 2 Te and a loss of Au|. For purposes of com- 

 parison the formulae of the three minerals should therefore be 

 written : 



Calaverite Au- 2 3 7 -AgfTe 2l . 



Goldschmidtite Au-^AgifTe^. 



Sylvanite- Au-^Ag-^-Te^. 



The next member of the series should have the formula : 

 AuV-Ag-¥-Te a4 



* This Journal, xlv, 1868, p. 314. + Ibid. 



t Am. Phil. Soc, xiv, 1874. p. 229. § Ibid., xvii. 1877, p. 117. 



1 16th Ann. Report U. S. G. S., Pt. II, p. 133. f Ibid. **Ibid. 



Note.— The mineral krennerite is a telluride of gold and silver richer in silver 

 than sylvanite, but the wide and remarkable variations in the proportions of its 

 constituents cause it to be regarded as of very indefinite composition. 



ff On the Chemical Composition of Chondrodite, Humite, and Clinohumite. 

 This Journal, xlvii, 1894, p. 188-206. 



