kansome.] ORE MINERALS. 77 
There remains over 5 per cent of superfluous water, which is not 
included in the foregoing calculation. The chemical analysis, how- 
ever, docs nol pretend to be more than approximate, and the luin- 
eralogical composition deduced from it is of similar character. 
ORE MINERALS. 
Under this head are included minerals generally mined as ores, 
together with some compounds of the heavy metals not of commercial 
value in this region. Unless otherwise stated, these minerals are 
characterized by a metallic luster. 
Pyrite.— Iron disulphide (V<><>). Isometric, pyritohedral. Mas- 
sive, granular, or in pentagonal dodecahedrons (pyritohedrons), octa- 
hedrons, or cubes, or in combinations of these forms. Pale-brass 
yellow. Hardness, •'». Specific gravity, 5. 
The isoinel ric sulphide of iron is common in all the ores of the dis- 
trict, and impregnates to a varying extent all of the country rock in 
the vicinity of the ore bodies. In some cases this impregnation has 
involved huge masses of rock, as in the Red .Mountain range, which 
owes its color to 1 lie oxidai ion of the pyrite that is scattered in minute 
crystals throughout the altered andesites and other rocks which 
compose the range. Large bodies of pyrite, formed in part by 
replacement of country rock, are known to exist in the lower work- 
ings of many of the abandoned mines of the Red Mountain district. 
Other large masses of crumbling granular texture occur near Ironton, 
in the Saratoga and Baltic mines, in great part replacing limestone. 
Pyrite, in beautiful octahedra embedded in kaolin, is abundant in the 
Zuhi mine, on Anvil Mountain. As a rule the pyrite, when occurring 
in large bodies with little or uo quartz, is not of sufficient value to 
pay for working. When, however, as in the Henrietta mine, it is 
associated with a considerable amount of chalcopyrite, it can some- 
times be mined at a profit. Associated with true vein quartz, espe- 
cially when the latter carries some free gold, the pyrite itself is 
usually sufficiently auriferous to repay treatment. In the Tomboy 
and Camp Bird mines the gold occurring in the pyrite is less in 
amount than that occurring free in the quartz. In the Gold King, 
however, the reverse is true. A large part of the gold in the Silver 
Lake mine is known to occur in pyrite. 
Pyrite in radially fibrous spherules, and at first supposed to be the 
orthorhombic sulphide of iron, marcasite, was noted in the dumps of 
the lied Cloud and Old Lout mines, and also occurred as small stalac- 
tites in cavities in the Genesee- Vanderbilt ore body. It was noted in 
radial spherules embedded in calcite at the Yellow Jacket claim on 
Bear Creek, near the northern edge of the quadrangle. Dr. H. N. 
Stokes, in the course of a chemical investigation on the iron sulphides, 
has shown that the foregoing radial forms are not marcasite but 
