548 Kraus and Goldsberry — Chemical Composition of 



accord with what should be expected from the progressive 

 changes which have been assumed in the chemical composi- 

 tion. 



Relation of the Minerals of the Fe„S-Cu^S Series to Other 

 Sulpho- Minerals. 



The general formula Cu x Fe 2 S y , given above, page 545, for 

 the Fe 2 S 3 -Cu 2 S series, may be further generalized so as to read 



M' x B/' / a S y , where again y = — -*• 3. Here M' is principally 



copper, silver, or lead, more rarely zinc, tin, mercury, thal- 

 lium, or bivalent iron, copper, cobalt or nickel. R/" maybe 

 ferric iron, arsenic, antimony, bismuth, or trivalent chromium, 

 nickel, or cobalt. Sulphur is sometimes partially replaced by 

 selenium. With M'-JR/'^Sy as a basis, it is now possible to 

 arrange a list of sulpho-minerals which show conclusively that 

 the compositions given for the various members of the Fe 2 S 3 - 

 Cu„S series, page 544, correspond directly to those of well- 

 established minerals. In this list the formulas are in nearly 

 every case those recognized by Groth.* 



eneral Formula M' x R"' a S y , 



where y = — -f- 3. 



Chalcopyrite 

 Lorandite 

 Miargyrite 

 Wolfsbergite 



Cu 2 Fe 2 S 4 



Tl a As s S 4 



Ag 2 Sb 2 S 4 

 Cu 2 Sb 2 S 4 



Emplectite 

 Scleroclase 



Cu 2 Bi 2 S 4 



PbAs 2 S 4 



(Sartorite) 

 Zinckenite 



PbSb 2 S 4 



Andorite 

 Galenobisruutite 



(Pb,Ag 2 )Sb„S 4 

 PbBi 2 S 4 



Alaskaite 

 Seleniferous 



(Pb,Ag 2 ,Cu 2 )Bi 2 S 4 



Galenobismutite 



PbBi 2 (S,Se) 4 



Daubreelite 



Fe'Cr,S 4 



Linnseite 

 Barracanite 



(Ni,Co)"(Ni,Co)'" 2 S 4 

 Cu"Fe a S 4 



Carrollite 



Cu // Co 2 S 4 



Barnhardtite 



Cu 4 Fe„S 5 



Dufrenoysite 

 Jamesonite 



Pb 2 As 2 S 6 

 Pb 2 Sb 2 S 6 



Kobellite 

 Cosalite 



Pb 2 (Bi,Sb) 2 S 5 

 PbBiS 



* Tabellariscke Uebersicht dcr Mineral en, 4th edition, 1898, also the 

 French translation with corrections and additions by Joukowsky andPearce, 

 1904. 



