112 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 192. 
mines. There are certain exceptions to what may be regarded as the 
normal or complete sequence. Thus the Congress mine appears to 
have had an ore consisting chiefly of enargite, with some bunches of 
galena, from the croppings downward. That the enargite at greater 
depth will gradually give place to iron pyrite, with diminishing 
amounts of chalcopyrite, can scarcely be doubted in the light of what 
is known of other deposits of this district. In the National Belle, 
enargite — in this case low grade — was encountered near the surface, 
but the oxidized ore in the siliceous knoll which forms the cropjrings 
appears to have been derived chiefly from galena, while below the 
third level (fig. 20) practically no pay ore was found. Explorations 
on the fourth level resulted only in the finding of small bunches of 
good ore and masses of crumbling iron pyrite carrying less than 0.1 
ounce of gold and about 5 ounces of silver per ton, with from 1 to 
3 per cent of copper. 
Chalcopyrite appears to have been usually good ore. It carries, 
theoretically, 34.5 per cent of copper, and in the Red Mountain dis- 
trict ran well in silver and gold; but its appearance in great quantity 
was apparently a precursor of the ultimate change to ores carrying 
chiefly the low-grade iron pyrite. 
Although there was on the whole a general change from argentif- 
erous lead ores to argentiferous and auriferous copper ores, and 
finally to slightly argentiferous and auriferous iron sulphide (pyrite), 
yet the progression was an overlapping and irregular one in detail. 
Iron pyrite and chalcopyrite occurred at practically all depths, wiiile 
galena in small bunches was sometimes. found far below the point at 
which it had ceased to be the principal ore. 
VALUE OF THE ORES. 
The ores of the stocks, like those of the lodes, vary widely in value. 
In 1883, 3,000 tons of ore extracted from the Yankee Girl averaged 
nearly $150 per ton. A lot of 10 tons from the richest stopes of the 
same mine carried 3,270 ounces of silver per ton and 29 per cent of 
copper, corresponding to an average value per ton of about $3,000. 
Much richer ore than this occurred in small quantities in the Yankee 
Girl and Guston. The average sales value per ton of the ore of the 
latter mine has been given in the table on p. 222 as $91.81 for a period 
of eight years. The highest annual average was $363.25 per ton, and 
the lowest $10.70. These, it should be borne in mind, are the prices 
for which the ore was actually sold to the smelters. Values based 
directly upon metallic contents, without reference to cost of treat- 
ment, would be higher. The highest annual average represents the 
ore from the rich stopes above the seventh level. The lowest corre- 
sponds to the low-grade pyritic ore of the deeper levels. The richest 
ore recorded from this district was some taken in 1891 from the Gus- 
ton at a depth of 378 feet, which carried 15,000 ounces of silver and 
