102 ECONOMIC GEOLOGY OF SILVERTON QUADRANGLE, [bull. 182. 
be associated with post-mineral fracturing and crushing and to have 
been deposited later than the bulk of the ore, In the New York City 
lode of the Silver Lake mine a sooty, amorphous sulphide of copper 
occurs with pyrite, chalcopyrite, galena, and sphalerite. This is 
probably of secondary origin, and although not a product of ordinary 
oxidation is yet considered as dne to descending waters percolating 
downward from the zone of weathering above. 
ORIGIN OF THE LODE ORES. 
Although the ores of the lode present many features not found in 
the stock deposits of the Red Mountain district, yet in the essential 
points of their origin they possess so much in common that it would 
be impossible to treat the two forms of deposit separately without 
much overlapping. Accordingly the question of the origin of the lode 
ores will be left in abeyance until the stocks have been described. 
VALUE OF THE LODE ORES. 
Generally speaking, the lode ores of the Silverton quadrangle are 
of low grade and require careful mining and milling to yield profit- 
able returns. The ores which are or have been worked vary in value 
from a probable minimum of about $6 to several thousand dollars per 
ton. The extremely high values, however, are for ores carrying free 
gold occurring only in small amounts in pockets in otherwise low- 
grade lodes, or in very small veins, such as the Golden Fleece. From 
the Sunnyside Extension mine, however, ore was obtained in carload 
lots carrying $1,500 per ton in gold alone, as shown by the smelter 
returns. In the Silver Lake Basin the ores worked probably vary 
from $8 or $10 to $60 or $70 per ton, according to the proportion of 
lead, silver, or gold which they contain. The average of the ore from 
the Iowa mine is not far from $12 per ton, although in places it may 
contain from 2 to 3 ounces of gold, thus affording much higher returns. 
The general average of the Silver Lake mine is probably higher, as 
half the value of its output is in gold. The ore of the Royal Tiger is, 
on the other hand, somewhat lower, the product being chiefly in lead. 
The North Star mine, on Sultan Mountain, was producing quantities 
of ore in 1882 carrying, according to the Mint reports, 40 per cent of 
lead and 70 per cent of silver. At the commercial values for that 
year this would mean an ore of about $120 per ton, gross value, or, at 
present prices, about $72 per ton. The Aspen mine is said to have 
produced one lot of 1,000 tons of ore containing 110 ounces of silver 
and 60 per cent of lead, which at present prices would correspond to 
about $110 per ton. The average value of the ore from this mine was, 
however, probably less than half this. The shipping ore from the 
Ridgway mine, containing finely disseminated argentite, is reported 
to average about $110 per ton, of which about 3 ounces is in gold and 
the rest in silver. The free-gold ore of the Tomboy mine averages 
about $20 per ton, of which $19 is in gold. The most uniformly rich 
