boutwell.] ORE DEPOSITS OF BINGHAM, UTAH. 115 
found to be tetrahedrite. In a mixture of the crystal and massive 
tetrahedrite Dr. Allen found 325 ounces of silver, which indicates 
that the mineral usually called ruby silver is the silver-bearing spe- 
cies of tetrahedrite, freibergite. 
Gold has been mined in Bingham in two forms — in its primary 
occurrence in country rock and in its secondary occurrence in detri- 
tal deposits. In the former it has been found in pay values included 
in sulphides, both in fissure ores, in pyrite, and possibly in galena 
and in tetrahedrite, and in replacement bodies in limestone. In 
the secondary occurrence rich gravel has been worked, though no 
free gold was obtained during the study of the camp. Unlike the 
primary gold, which is said to have been rough and jagged, placer 
gold is said to occur in thin beaten scales and washed nuggets. Flour 
gold has been found to be evenly distributed through the gravel for 
a distance of 30 feet above bed rock. In the early days when gold 
ores were mined from the silicified superficial portions of the great 
mineralized limestones and treated in stamp mills, only a portion of 
the gold was found to be free and no successful process was secured 
for treating the remainder of the gold content. In the present low- 
grade copper ores gold is an important associate, for it is the gold 
contained in these ores, low as it is, which renders more than one 
Bingham property a commercial possibility. 
Zinc is present in the gangue of lode ores and is most abundant in 
those which lie within porphyry. It forms uneven layers roughly par- 
allel to those of its associates, and irregular bunches and stringers inter- 
mixed with them. A few minute crystals of the light honey-yellow 
variety and of the black variety occur in vugs in veins, but by far the 
greater portion of this mineral is of the blackjack type and occurs 
occasionally granular, but usually massive cleavable. The Bingham 
occurrences of zinc deserve the attention of owners (see p. 121). 
Some other minerals which under suitable commercial conditions 
are of economic value occur here sparingly. Molybdenum occurs in 
grains and bands in the porphyry of the Bingham laccolith, but in 
too small quantities to be of economic value. Gypsum is found 
in fibrous and selenitic form in small amounts in calcareous shale. 
Barite in radiating plates lies at the cores of some veins. Iron is 
found besides in copper sulphides, in magnetite, specularite, and 
limonite, but does not assume commercial importance. In brief, 
then, the valuable ores of Bingham are the copper-iron-gold-silver 
replacement ore, and the lead-silver-copper-gold lode ore. 
Values. — The values of the Bingham ores average very low. Pay 
ore is widely distributed; prospecting in country rock in any part of 
the camp rarely fails to disclose some metals, but bonanzas have 
rarely been found. With very few exceptions the ore which is being 
mined to-day carries such low values as to render its successful 
extraction and reduction either a close-smelting or a concentrating 
