28 Penfield and Frenzel — Identity of Ghalcostibite, etc. 



The composition Cn 2 S . Sb 2 S 3 was established by an analysis by 

 H. Hose,* and the crystals were measured and determined to 

 be orthorhombic by G. Hose,f who identified two prisms and a 

 pinacoid in one zone, but as no terminal faces were observed, 

 the axial ratio could not be fully determined. The name 

 rosite was assigned to the species in 1841, by Huot,J but on 

 account of its similarity to roselite, it has not been generally 

 accepted. In 1847 the mineral was called chalcostiMte by 

 Glocker,§ and in 1849 wolfsbergite, by Nicol.| (blocker's 

 name thus antedates Nicol's, and there seems to be no reason 

 for not accepting it, although wolfsbergite is in common use. 



Terminated crystals of chalcostibite from Wolfsberg are 

 very rare, and we are indebted to Laspeyres^f for the only 

 description of them, and for the determination of the axial 

 ratio. In order to show a crystallographic relation between 

 chalcostibite and the similarly constituted minerals zinkenite, 

 PbS . Sb 2 S 3 ; sartorite, PbS . As 2 S 3 and emplectite, Cu 2 S . Bi 2 S 3 , 

 the crystals were orientated so as to make the perfect cleavage 

 basal, and the prominent prismatic development parallel to the 

 crystallographic axis b. 



The forms that were identified by Laspeyres are as follows : 



c, 001 d, 101 /, Oil p, 7-14-8** 



e, 307 g, 201 q, 863 r, 7*21-27** 



The axial ratio was derived from measurements of the pyra- 

 mid p, and was found by Laspeyres to be a : b : c — 0-5283 : 1 : 

 0-6234, but by giving to p the indices 6-12-7 instead of 7*14-8, 

 the axial ratio becomes 0*5283 : 1 : 0*6364. Some of the 

 important measurements made by Laspeyres will be found in 

 column I, in the tables on page 34, et seq. 



Chalcostibite {guejarite) from Guejar in /Spain. — The iden- 

 tity of guejarite as a distinct mineral species had been based 

 upon the following analysis by Cumenge : ft 



Found. Theory for Cu 2 S . 2Sb 2 S 3 . 



s 



25*0 







27-0 



Sb 



58*5 







57*8 



Cu 



15*5 







15-2 



Fe 



.... 0*5 











Pb 



_ tr. 







- -- 





99*5 



ioo-o 



♦Ibid, p. 361. 

 $ Mineralogy, i, p. 19*7. 

 1 Mineralogy, p. 484. 

 "** Ab will be shown later, 

 tively. 



f f Loc. cit. 



■f Ibid, p. 360. 

 8 Syn., p. 32. 



f Zeitschr. Kryst., xix, p. 428, 1891. 

 7 14 8 and 7 21 27 should be 6-12-7 and 134, respec 



