boutwei,!,.] PARK CITY MINING DISTRICT, UTAH. 39 
from the mines to the Rio Grande Western system for shipment to the 
custom smelters in the Jordan Valley. These perfected plants and 
extensive operations, by which mining expenses are reduced to a 
minimum, are rendered possible by a wise consolidation of interests. 
Thus large tracts are owned by single companies; the bulk of the 
output for the last year was supplied from two properties, and the 
reputation of the camp rests upon the record of five great properties. 
Character of the ores. — The values of the Park City ores (named in 
the order of their importance) lie in their silver, lead, copper, and 
gold contents. Silver has been reported in the form of several silver 
minerals, and doubtless lies principally in the galena and gray copper. 
Lead is present chiefly in the form of massive cleavable galena in the 
sulphide zone, and of crystalline cerussite, amorphous auglesite, and 
complex oxides in the zone of surface alteration. Copper occurs for 
the most part as gray copper (tetrahedrite) in the sulphide zone, and 
in the form of the blue and green carbonates (azurite and malachite) 
in the oxidized zone. The mineralogical character of the gold is not 
known, though it may occur as an impurity in pyrite. Zinc is a 
common associate in the fissure ores. 
Superficial alteration has descended to great depths. Some ore 
bodies in limestone have been almost entirely altered to oxides, car- 
bonates, and sulphates to the depth of 900 feet below the present 
surface, and the effects of oxidation may be observed upon the walls 
of sulphide ore bodies and adjacent to fissures cutting them, even to 
a depth of 1,300 feet. At present both the oxidized and the sulphide 
ores are mined. 
These include large amounts of both first-class smelting ore and 
milling ore. Several bodies of very high-grade ore — bonanzas — have 
been discovered. Ore from the upper levels, 100 to 400, on a great 
lode of this district is reported to have run from $40 to $700 a ton, 
with an average of $130, and in 188G "the best" Ontario "ore was 
sold to smelters and averaged $94.82 per ton. Ores of lower grade 
were milled averaging 54.32 ounces of silver."" The average value 
of crude ore shipped during the year 1902 from one of the principal 
properties of the camp was between $28 and $29 per ton. 
Occurrence of ores. — The Park City ores do not appear to be gener- 
ally distributed throughout the region in small amounts, but rather 
to be localized in certain well-defined occurrences in large bodies of 
pay grade. Three main types of occurrences have been recognized — 
fissure ores, replacement ores, and contact ores. In the first the ore 
carries either silver and lead, with or without zinc and gray copper, 
or gold with some silver, and occurs between well-defined fissure 
walls. In the second the ore holds silver and lead values chiefly and 
takes the form of elongated lenses within limestone, roughly parallel 
aAlmy, T. J., History of Ontario mine, Park City, Utah: Trans. Am. Inst. Min. Eng., vol. 16, 
p. 37. 
