34 MINEEALOGY. 



" there is much fire in it," referring to its readily strik- 

 ing fire with steel. It occurs, when crystallized, in the 

 primary forms of cube, octahedron, and dodecahedron 

 (Figs. 9, 10, and 11), and in a variety of secondary forms. 

 Its color is a bronze-yellow, and the lustre is often bril- 

 liant. As the lustre is metallic, it has been often supposed 

 by common people to be gold, and specimens which have 

 been found are every now and then taken to some person 

 of known scientific character in the community for in- 

 quiry on this point. It has therefore received the name 

 of " fool's gold." The distinction between it and gold 

 is, however, easily made, for the pyrites is very hard, is 

 not malleable like gold, and on the application of strong 

 heat it gives off sulphurous fumes. It is not much prized 

 as an ore for obtaining iron, because of the difficulty of 

 ridding it entirely of the sulphur ; but it is much used 

 for obtaining sulphate of iron (green vitriol or copperas), 

 sulphuric acid (oil of vitriol), and sulphur. There is a 

 magnetic iron pyrites, which is softer and liable to tar- 

 nish. There is also an arsenical iron pyrites, nearly half 

 of which is arsenic. Its color is silver- white, with a shin- 

 ing lustre, and on being struck with steel it gives a spark 

 with a garlic odor. 



51. Copper Pyrites. This is not a sulphuret of copper, 

 but of copper and iron, nearly one third of it being iron. 

 It has a deeper color than iron pyrites, is softer, yielding 

 readily to the knife, and does not strike fire with steel. 

 Its color is such that it looks like gold, but it is at once 

 distinguished from it by its crumbling under the knife. 

 Much of the metal copper is obtained from this ore, and 

 sulphate of copper (blue vitriol) is largely manufactured 

 from it. There is a copper ore called copper glance, a 

 sulphuret in which the proportion of iron is very small. 

 It is of a lead-gray color. There is also a sulphuret of a 

 dark steel-gray color, of a very compound character, there 

 being in its composition six ingredients sulphur, copper, 

 antimony, arsenic, iron, zinc, and silver. Sometimes the 



