ORDER X. KIIOMBOIIEDRAL IRON- PYRITES. 465 



pyrites are identical. Three analyses, two of them by 

 HATCHETT and one by BERZELIUS, have yielded, 



Iron 46-40 45-66 45-07. 



Sulphur 53-60 54-34 53-35. 



Manganese 0-00 0-00 0-70. 



Silica 0-00 0-00 0-80. 



Like the hexahedral Iron-pyrites, its chemical formula is 

 Fe S 4 . Before the blowpipe it also comports itself like that 

 species. Some of its varieties are particularly subject to 

 decomposition. 



3. The prismatic Iron-pyrites is less frequently met with 

 in nature than the hexahedral one, and seldom without it ; 

 it seems most plentiful in beds of coal and the accom- 

 panying strata of clay. It is found likewise in metalliferous 

 veins with ores of silver, lead, and copper, also with rhom- 

 bohedral Lirne-haloide, octahedral Fluor -haloide, prismatic 

 Hal-baryte, and other species. 



4. Radiated, hepatic, and cellular pyrites are found in 

 several parts of Saxony, particularly near Freiberg, Mem- 

 mendorf, &c., hepatic pyrites at Johanngeorgenstadt, radia- 

 ted and spear pyrites at Joachimsthal, Littmitz, and Altsat- 

 tel in Bohemia, the former also at Schemnitz in Hungary 

 and Almerode in Hessia; cockscomb pyrites in Derbyshire. 

 Spear-pyrites and radiated pyrites in beautiful stalactitic 

 groupes are found in Cornwall. Several varieties are be- 

 sides met with in the Hartz, in the Black Forest, in 

 France and other countries. 



5. The varieties of this species are very useful in ma- 

 nufacturing sulphur, sulphate of iron and sulphuric acid. 



1. RHOMBOHEDRAL IRON-PYRITES. 



Rhomboidal Iron-pyrites or Magnetic Pyrites. JAM. 

 Syst. Vol. III. p. 305. Man. p. 274. Magnetic Iron- 

 Pyrites. PHILL. p. 221. Magnetkies. WERN. Hoffm. 

 H. B. III. 2. S. 212. Magnetkies. HAUSM. I. S. 144. 

 Leberkies. LEONH. S. 330. Fer sulfure' ferrifere. 

 HAUY. Tabl. comp. p. 98. Fer sulfure' magne'tinue. 

 Traite, 2de Ed. T. IV. p. 64. 



TOL. II. 2 o 



