724 



GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



ANALYSES XL AND XLI. MATTES. 

 Elemen tary. 



Hittioiial. 



The writer ha* described in the Bulletin <le la Suciete Chimique de Paris a peculiar mineral Ibinied of arsenic 

 aulphuret of nickel and chrome-iron oxide, which cci tuinl y prchents a great analogy with the mattes. 



Lead aud iron mattes arc not the only ones which form iu the furnace. A thud 

 one, which is much more interesting, may be called the calcium matte. This matte is 

 formed, like its congeners, of a sulphide, .sulphide of calcium, aud of magnetic oxide 

 of irou, crystallographically combined. This matte has not been found in an isolated 

 state, but it exists iu combination with scoriae, and the product thus formed is pre- 

 cisely the slag of Leadville. So that the best definition of slags that can be given is 

 the following: Slags are compounds of scoriae or silicates and of calcium mattes, aud, 

 like most of the furnace products, they are formed of chemical compounds crystallo 

 graphically combined. 1 



1 Although Jlr. Guyjird's delinitiou may perhaps seem somewhat obscure to the reader, I do not 

 feel Mil'Jcieully certain of his meaning to attempt to modify it, aud therefore leave it iu his own winds. 

 (S. F.E.) 



