iro^ okt:s. 233 



rites is sometimes heated in clay retorts, by which about 17 

 per cent, of sulphur is distilled over and collected. The ore 

 is then thrown out into heaps, exposed to the atmosphere, 

 when a change ensues, by which the remaining sulphur and / 

 iron become sulphuric acid and oxyd of iron, and form sulphate I 

 of iron or copperas.* The material is lixivated, and par- 

 tially evaporated, preparatory to its being run off into vatsj 

 or troughs to crystallize. | In other instances, the ore is 

 coarsely broken up and piled in heaps and moistened. Fuel 

 is sometimes used to commence the process, which after 

 wards the heat generated continues. Decomposition takes 

 place as before, with the same result. At Strafford, Ver- 

 mont, about 1000 tons of copperas have been produced an- 

 nually, valued at 2 cents a pound, or $40,000. The quanti- 

 ty manufactured might easily be much increased. The py- 

 rites of Cape Sable, Maryland, also affords large quantities 

 of copperas. The lixivated liquid is often employed in Ger- 

 many for the production of sulphuric acid ; at a red heat, the 

 acid passes off, leaving behind a red oxyd of iron, which is 

 called colcothar. X Cabinet specimens of pyrites, especially 

 granular or amorphous masses, often undergo a spontaneous 

 change to copperas, particularly when the atmosphere is moist. 



The name pyrites is from the Greek pur, fire, because, as 

 Pliny states, '* there was much fire in it," alluding to its strik- 

 ing tire with steel. This ore is the mundic of miners. 



White iron pyrites. This ore has the same composition as common 

 iron pyrites, but crystallizes in secondaries to a right rhombic prism ; 

 M : M=106° 36'. The color is a little paler than that of common py- 

 rites, and it is more liable to decomposition; hardness the same ; spe- 

 cific* gravity 4*6 — 485. Radiated pyrites, hepatic pyrites, cocks- 

 comb pyrites, (alluding to its crested shapes,) and spear pyrites are 

 names of some of its varieties. It occurs in crystals at Warwick and 

 Phillipstown, N. Y. Massive varieties are met with at Cummington, 

 Mass. ; Monroe, Trumbull, and East Haddam, Conn. ; and at Haver- 

 hill, N. H. 



PYRRHOTINE. MAGNETIC PYRITES. SulpJlltret of Iron, 



Hexagonal. Occurs occasionally in hexagonal prisms, 

 which are often tabular ; generally massive. 



Color between bronze -yellow and copper-red ; streak dark 



How is sulphuric acid obtaine ? and what is colcothar 1 What is the 

 origin of the name pyrites ] What is the crystallization and appear 

 ance of magnetic pyrites? 



* This change consists in the union of oxygen with the sulphur an 

 iron. 



UMkM 



I . 



