Penfield and Frenzel — Identity of Chalcostibite ^ etc. 31 



Specific gravity 4-96. 









Theory for 



I. 





Ratio. 



II. Ill, 



Cu 2 S . Sb 2 S s 



S. 26'28-t- §2 = 





•821 4'00 



S 26-12 



25-87 



Sb 48-86-M20 = 





•407 1-995 



Sb 48-50 48-44 



48-50 



Cu 24'44-H 26-8 = 



•193 ) 





Cu 25-92 25-23 



25-63 



Pb -58-7-207 = 



•002 | 



■•202 0'995 



Pb .... -32 



_ _ - - 



Fe -42-r- 56 = 



•007 J 





Fe -49 



2 n «i8 







100-58 





















100-78 



100-00 



In the first analysis the ratio of S : Sb : (Cu 2 -f-Pb+Fe) is 

 almost exactly 4:2:1, which is that demanded by the chalco- 

 stibite formula Cu 2 S . Sb 2 S 3 . The results of the second and 

 third analyses are almost identical with those of the first, so 

 we are thus enabled to establish beyond all doubt the identity 

 in chemical composition of guejarite with chalcostibite. 



Chalcostibite from Huanchaca, Bolivia. — On the specimen 

 sent to ns by Mr. Hohmann, the chalcostibite occurred as pris- 

 matic crystals averaging about l mm in diameter and 2 mm in 

 length, which were attached to a gangue of quartz and pyrite 

 vein material. Some massive tetrahedrite was also present, but 

 the chalcostibite crystals were not found directly upon it. 

 Although the crystals were isolated and quite numerous, only 

 a few were implanted so that they could be removed and used 

 for measurement. Doubly terminated ones were not observed. 

 The crystals are quite highly modified, and the forms that have 

 been identified are given in the following table, where those 

 which are new are indicated by an asterisk : 



c, 001 



h, 203* 



t, 021 



v, 133* 



I, 130* 



d, 101 



u, 061 



7T, 265* 



A, 209* 



i, 302* 



#, 863 



p, 263* 



A l5 207* 



g, 201 



p, 6-12-7 



o-, 4-12-5* 



A„ 205* 



5, 065* 



/x, 136* 



r, 261* 



The large development of the pyramids p and q, whose 

 indices are complicated, corresponds almost exactly with the 

 description given by Laspeyres of the occurrence of the same 

 found on the crystals from Wolfsberg. These pyramids were 

 free from striations and vicinal developments, and gave excel- 

 lent reflections. A few crystals were observed which have the 

 habit represented in fig. 3, by a projection upon the pinacoid 

 010. All the pyramidal forms given in the foregoing table 

 were observed upon a single crystal of this habit, but, of the 

 faces in the zone between c and Z, all of which were quite 

 small, p, v and <r are not represented in the figure. 



