Decomposition of Iron Pyrites. 



389 



Density of Marcasite. 



Locality. 



Analyst. 



Sp. Gr. 



Kind of Material. 





r 



4.826 

 to 



4.837 



Common radiated masses, 

 from the clay of the Brown 

 Coal. 







4.845 



Octahedra, all drusy. 



Gross-Allmerode, 

 Hesse. 



F. Kohler, 51 { 



4.859 



to 

 4.907 



Octahedra, with smooth 

 faces. 





- 



4.879 



Cubo- octahedra. 





.. 



4.919 



Cubes. 



Littmitz, Bohemia. 



Breithaupt. 54 



4.847 





<. 



0. Ranimelsberg. 5 * 



4.878 



Speerkies. 



.. 



Mohs. 



4.857 





Joachimsthal. 



0. Ranimelsberg. 5 - 



4.865 





Schemnitz, Hun- 



G. Rose. 53 



4.848 



Speerkies. S.G., at 11° ;j R. 



gary. 



Breithaupt. 5 - 1 



4.878 





Freiberg. 



,, 



4 601 





Derbyshire. 



5 2 



j 4.879 



Kamkies. S. G.. at 12° R. 



Iii considering, these analyses, it is safe to say that no exami- 

 nation of massive, radiated or granular forms (strahlkies, speer- 

 kies, etc.), nor of paramorphs after pyrite, can be relied upon, 

 as made upon pure material ; for in all such instances there is a 

 suspicion — often the visible evidence — of the intermixture of 

 more or less pyrite, causing the extreme variations in density. 



51 Pogg. Ann. (1828), XIV, 91. 



53 Zeitschr. d. geol. Ges. (1864), XVI, 268. 



53 Pogg. Ann. (1849), LXXIV, 291. ■ 



54 Erd. Jour. f. pr. Ch. (1835), IV, 257. 



