172 



DESCRIPTIONS OF MINERALS. 



It is a constituent of nearly all meteorites, and the chief 

 ingredient in a large part of them ; and in this state it is 

 with a rare exception alloyed with nickel, and with traces 

 of cobalt and copper. The Texas meteorite, of Yale College, 

 weighs 1,G35 pounds ; the Pallas meteorite, now at Vienna, 

 originally 1,000 ; but one in Mexico, the San Gregorio 

 meteorite, is stated to weigh five tons ; and one in the dis- 

 trict of Chaco-Gualamba, S. A., nearly fifteen tons. Meteoric 

 iron often has a very broad crystalline structure, long lines 

 and triangular figures being developed by putting nitric acid 

 on a polished surface. The coarseness of this structure dif- 

 fers in different meteorites, and serves to distinguish speci- 

 mens not identical in origin. Nodules of troilite (FeS), 

 and schreibersite (iron phosphide) are common in iron me- 

 teorites. Meteoric iron may be worked like ordinary malle- 

 able iron. The nickel diminishes the tendency to rust. But 

 some kinds contain iron chloride, or are open in texture, and 

 rust badly. 



Pyrite. — Iron Pyrites. Iron Bisulphide. 



r 



j? 



Isometric. Usually in cubes, the striae of one face at right 

 angles with those of either adjoining face, as in fig. 1. Also 



