68 



It forms many varieties of crystallizations. T/ie upper 

 figure shows a group of cubes : the larger one appears some- 

 what laminated in the structure^ and is nearly covered as it 

 were with a thin case. They are often quite smooth, but 

 are more frequently found with straight lines or striae on the 

 faces, alternating with the faces next to each other, but 

 agreeing with the opposite sides or faces. The cubes are 

 often larger than those here figured. 



Under the blowpipe the odour of sulphur is very sen- 

 sible, and a magnetical oxide of iron is to be produced. It 

 scintillates with steel. 



The lower figure from Redruth, m Cornwall, with little 

 cubes, piled like clubs, and somewhat varying in colour, 

 perhaps contains a little more copper. Mr. Kirwan says a 

 small portion of copper is always present in pyrites. The 

 upper part being paler than the lower is a sort of indication 

 ©f its holding most iron. Spec. Grav. 4,1006 — 4,7404, 



