268 MINERALS YEARBOOK, 1967 
 
 The Bunker Hill Co. stockpiled Crescent mine silver concentrates because
of the strike at Asarco's East Helena smelter. The $215,000 aircooling plant
on the 3100 level of the Crescent mine went into operation in August. Bunker
Hill began the first of three long diamond-drill holes to test a mineralized
area on Yreka United ground. 
 Six silver mines in the State reported production of 434,898 tons of ore
containing 11,919,437 ounces of silver. Significant development included
the following districts. 
 Evolution District (Shoshone County). 
-----Production of silver from the Sunshine mine was 5 percent higher than
in 1966. Approximately 150 ounces of gold, 1,156 tons of copper, 584 tOns
of lead, and 122 tons of zinc also were recovered from 239,915 tons of ore.
The No. 10 shaft was deepened to below the 5200 level, and pockets and stations
were completed on the 5000 and 5100 levels. A new service hoist was installed,
and development work continued on the 4800 level. 
 Sunshine Mining Co. continued work on the exploration crosscut to the Bismarck
property from the 2700 level of the Sun Con area, completing over 3,000 feet
toward the projected Bismarck vein. 
 Hecla Mining Co. recovered 528,000 ounces of silver and 129 tons of copper
from 26,869 tons of ore from the Silver Summit mine. Development work was
limited to the 3600, 3800, and 4000 levels. Production decreased from the
previous year, but the average grade of ore improved as a large proportion
of the production came from stoping rather than from development work. 
 Placer Center District (Shoshone County) .—Asarco recovered over 2
million ounces of silver concentrates and 730 tons of copper from the .Galena
mine prior to shutdown as a result of the strike on July 15. A program for
expansion of mine facilities, centered on the new No. 3 shaft, was nearing
completion when interrupted by the strike. 
 Yreka District (Shoshone County).— The Bunker Hill Co. reported to
its stockholders that the Crescent mine produced 25,383 tons of ore averaging
56.13 ounces of silver per ton. Approximately three-fourths of the silver
produced in this period came from one high-grade vein developed on the 3300
and 3500 levels. Installation of a new refrigeration unit 
was completed at the mine during the year. 
 Bayhorse District (Custer County).— Increased production of 68,500
tons of silver ore resulted in another record high year for the Clayton Silver
Mines Clayton mine. Approximately 226,000 ounces of silver, 28 tons of copper,
812 tons of lead, and 400 tons of zinc were recovered from the Clayton ore.
Mining continued throughout the year in the 800 level North stope. The smelters
to which Clayton sells its lead and zinc concentrates were shut down by the
copper strike, but the Clayton mine continued operating and stockpiled the
concentrates during the interim. 
 
 Tungsten.—Value of Idaho tungsten ore production increased from $1,000
in 1966 to $175,000 in 1967 as 68 tons of tungsten concentrates was produced
from three mines. Salmon River Scheelite Corp. accounted for over 80 percent
of the production from the Tungsten Jim mine in Custer County. Two Valley
County properties, the Golden Gate mine and the Skipper mine, accounted for
the rest of the State's total. 
 
 Vanadium.—Output of vanadium was 24 percent above that produced in
1966. Ferrophosphorus from the Monsanto Co. elemental phosphorus plant at
Soda Springs was processed at the nearby KerrMcGee facility. Vitro Chemical
Co. utilized a similar ferrophosphorus byproduct from the FMC Corp. operation
in Power County for use at its Salt Lake City, Utah, vanadium recovery plant.
The raw material for the Power County plant was derived from phosphate deposits
in Bingham County. 
 
 Zinc.—Output of zinc declined 7 percent, following the trend of its
coproduct lead, and lower prices resulted in a $2 million decline in value,
down 12 percent from the 1966 value. The Bunker Hill mine, combined with
Hecla Mining Co.'s Star-Morning Unit area, accounted for over half of the
State's output. 
 At the Bunker Hill zinc plant, major items of the planned expansion were
completed and placed in operation. A 350ton-per-day flash roaster, electrolytic
zinc plant cooling towers, and a continuous leach circuit were completed.
Zinc concentrates were unloaded at a new materials handling building, and
construction