380 



Decomposition of Iron Pyrites, 



Density of Pyrite. 



(CONTINUED.) 



Locality. 



Analyst. 



Sp. Gr. 



Kind of Material. 







r 



4.872 



Crystals with strongly stria- 



Tavistock, Devon- 

 shire. 



Kenngott and V. 

 v. Zepharovich, 33 



j 



4.870 

 4.870 

 4.949 



ted faces, quite pure in ap- 

 pearance, but showing, un- 

 der a lens, the inclusion of 







I 



4.833 



little gray grains. 







r 



i 



5.151 

 5.181 



Crystal. 



Locality unknown. 



" 



1 



5.178 



" 







4.902 



" 







i 



4.830 



Crystal with upper surfaee 

 colored brown. 



Steiermark. 



" 





4.989 





Johanngeorgen- 



Breithaupt. 34 





4.960 



Cube. 



stadt. 











Kamsdorf near 



" 





5.000 



" 



Saalfeld. 











Kongsberg, Norway 



" 





5.158 



" 



Gouverneur, N. Y. 







4.863 



Pale bronze-colored, radia- 

 ted, botryoidal, nickelife- 

 rous. 



Annaberg. 



Breithaupt. 34 





5.022 





Schneeberg. 







5.029 





The results above given, concerning pyrite, afford us little 

 means of exact comparison between chemical composition and 

 density. Most analyses of the mineral have been made upon 

 granular or massive impure varieties, for commercial purposes. 

 In some cases selected crystals have been taken, but in none 

 have we the means of judging by complete analyses, color, 

 hardness, or other physical properties, how far the figures for 

 density have been increased by the presence of gold, copper, 

 etc., in the pyrite, or decreased by lighter impurities (quartz, 

 etc.), by partial decomposition, by intermixture with other 

 pyrites, or by the cavities enclosed in some beautiful crystal, 



33 Kenngott's Min. Notiz. (1855), No. 11. 

 3 ^ Erd. Jour. f. pr. Chem. (1835), IV, 257. 



