Eaki.e.] 



Mineralogical Notes. 



325 



combinations of the octahedron and cube, the former predom- 

 inating. Many of them, however, have the cubo-octahedral edges 

 beveled by narrow faces which measurements show is the 

 trapezohedron, /?(322). The measurements with the reflecting 

 goniometer were: — 



Measured. Calculated. 



(ill): (ill) 70° 31' 1 7°° 3 2 ' 



(in) : (in) 109 24' 109 28' 



(in): (322) 1 1° 22' 1 i c 25' 



The typical appearance of these crystals is illustrated in 

 Figure 6, PI. 9. 



The analysis shows the composition of the crystals to be as 

 follows: — 



Calculated for Pb Te. 

 Per cent. Per cent. 



Te 32.5 377 



Pb 65 62.3 



Ag Traces up to o. 1 

 An None 

 Fe Trace 

 Se 

 S 



In one portion gold to the amount of 6 per cent was found, but 

 this was doubtless due to a mechanical admixture of the intimately- 

 associated gold, as the purer material gave no test for gold. The 

 analysis differs somewhat from the theoretical composition of 

 altaite, yet it is sufficiently near to indicate that the crystals are 

 altaite. 



Some of the gold is in the form of highly-distorted octa- 

 hedrons, and partial analyses of these crystals gave 91.2 percent 

 to 94.2 per cent gold. 



Crystals of altaite are exceedingly rare in occurrence, and only 

 the cube form has heretofore been observed. 



Massive altaite showing cubic cleavage occurs at the Stanislaus 

 Mine, Calaveras County, and has also been reported from the 

 Golden Rule Mine, Tuolumne County, by Genth * 

 University of California, 



October, 1 go 1. 



*F. A. Genth, Amer. Jour. Science, 1868, 45, 312. 



