northeast. Holdings consist of the following claims: McClure, Andrews, Banner, Everett, Hope, and Poverty, totaling 160 acres; patented. Development consists of a crosscut tunnel 500 feet in length. Owners, Mount Shasta Gold Mines Corporation.

Bibl: State Mineralogist Report XIV, p. 769; Bull. No. 50, p. 110.

Minnie Haley Group of Mines is located on the west slope of Horse Mountain, in Sec. 24, T. 34 N., R. 4 W., 13 miles northeast of Heroult. Elevation is 1800-2000 feet. Owners are James Doyle and George G. Dean of Redding. Holdings consist of 8 claims.

The ore is found along epidote dikes which occur in the Dekkas andesite on the western slope of Horse Mountain. The ore is chalcopyrite associated with iron pyrite in quartz gangue, and carries values in gold and silver.

Developments consist of four tunnels from 20 to 150 feet in length. Two men employed on development work.

Bibl: State Mineralogist Report XIX, p. 92.

Mountain Copper Company's property includes the Iron Mountain and Hornet mines, comprising several hundred acres of patented land located in Secs. 34 and 35, T. 33 N., R. 6 W., 11 miles by railroad northwest of Keswick. Owners, Mountain Copper Company, 3 Lombard St., London, England. Sir Charles Fielding, president; A. N. Frewer, secretary. Pacific coast office, 332 Pine St., San Francisco. W. F. Kett, general manager; M. F. Murphy, superintendent. Mine offices are at Mathewson, California.

Since the Fourteenth Report of the State Mineralogist, 1914, the Iron Mountain Mine operated until the early part of 1921, when operations were suspended, due principally to the low price of copper. In 1915, a 500-ton flotation plant was built at Minnesota Station on the Iron Mountain Railroad for the purpose of treating the low-grade ores from the Iron Mountain Mine. The Hornet Mine has been under continuous operation, producing from 400 to 500 tons of pyrite ore per day. A new crushing and sizing plant, with a capacity of 600 tons per day, was constructed and put in operation in October, 1920. In February, 1922, an aerial tramway from the Hornet Mine to Mathewson, a station on the Southern Pacific Railroad, was put in operation. It is 2 miles in length and has a capacity of 100 tons per hour, and replaces the old Iron Mountain Railroad, used by the company for ore shipments for many years. The company ships 500 tons of pyrite ore daily to chemical plants near San Francisco. The Keswick smelter has been dismantled and the shops removed to Mathewson.

Hornet Mine. This mine lies to the north of the Iron Mountain Mine, on Boulder Creek, where a gossan capping, with a general strike of N. 30° E. is exposed, indicating the position of an immense orebody of pyrite which has been developed by a number of tunnels. One tunnel 300 feet above Boulder Creek is 500 feet in length on the eastern edge of the orebody. A lower tunnel, a short distance above the creek, follows the greater part of its length of 1600 feet along the western border. The main haulage tunnel is 10 by 10 feet, 3000 feet in length and is 180 feet below the old adit.

The ore occurs in a large fissure along a shear zone in the rhyolite. The lens of ore developed is several hundred feet in length; width and depth are undetermined. The general strike of the orebody is N. 30° E., with a dip almost vertical. The ore is nearly pure iron pyrite with not over 1% to 2% silica, the average copper content being 0.7% and the sulphur content 45% to 48%. The ore is mined by combination of shrinkage and caving method. Estimated tonnage of ore developed is about 5,000,000 tons. Ore is hauled from the mine by electric motor in trains of ten 7-ton cars to a bin at the crushing plant which has a capacity of 700 tons. From the bin the ore passes through a No. 6 Gates gyratory breaker, and is conveyed to a 4-foot trommel over the railroad bins, where it is screened into three sizes, namely: minus 3-inch; plus 3-inch; minus 13-inch; plus 13-inch, which includes pieces up to 4-inch maximum. About 10% to 20% of ore coming from the mine, containing waste, is classed as second-class ore and is dumped into separate bins.

This ore is fed to a 4 x 12-foot trommel having screens with 1-inch openings. The oversize from the trommel goes to the picking belt conveyor, where the waste is sorted out. This waste is conveyed to the waste dump, while the clean ore goes to a No. 6 Gates gyratory crusher. The undersize from this trommel goes to the jig storage bin. From these bins the ore is fed by means of a Challenge disc-feeder to four one-compartment Harz jigs. The concentrates from these jigs flow to a special dewatering bin at the railroad. The 1- to 4-inch size material is shipped to the Standard Oil Company, at San Francisco, and the mine's 3-inch material to the General Chemical Company, at San Francisco. The Standard Oil Company returns the pyrite cinder to the company's smelter at Martinez, where it is leached and the copper extracted. The Hornet Mine is the only property owned by the company that is under production. However, it is the company's plan to resume operations at

Iron Mountain Mine when the price of copper will warrant reopening it. Two hundred men are employed.

Bibl: State Mineralogist Report XIV, pp. 769-770; Bulletin No. 50, pp. 70-78.

Iron Mountain Mine. This mine has been operated since 1880, it being the pioneer copper mine of the Shasta copper belt. The company

controls a large acreage on Iron Mountain, between Slick Rock and Boulder creeks. Elevation varies from 2400 to 3200 feet. The Iron Mountain fissure occurs in the rhyolite and has a course of N. 70° E., and dips 75° W.

The ore deposits of Iron Mountain consist of immense masses of sulphides, mainly underlying a gossan capping 300 feet in width, but in places the ore occurs in and under rhyolite. The principal ore mass developed lies on the southern slope of Iron Mountain above Slick Rock

Creek. This orebody was 800 feet long, from 100 to 400 feet wide, and 600 feet in depth below the gossan outcrop. It contained about 2,000,000 tons of ore of all grades. The ores are chalcopyrite associated with massive pyrite carrying from 2.5% to 5% copper, with $2 in gold and silver per ton. The pyrite orebody has been worked out, but it is reported the present ore reserves amount to 300,000 tons of siliceous copper ore carrying 3% copper. (Plate III.)

Developments consist of thousands of feet of tunnels, the principal tunnels through which the ore was mined being No. 8 mine tunnel, driven N. 10° W. 3000 feet, and at a higher elevation, the Confidence tunnel, driven N. 40° W. several thousand feet. The Complex Mine, which is located east of Confidence tunnel at an elevation of 3150 feet, has been driven north 3000 feet, intersecting the Iron Mountain fissure. An incline tram connects this mine with bunkers on the Iron Mountain Railroad, a distance of 1500 feet.

From 1915 to 1921, the principal production from the mine has been siliceous ore running 2%, which was treated in a 500-ton flotation plant.

Flotation Plant.

The crushing plant is at Iron Mountain Mine. The ore is delivered by electric haulage from No. 8 tunnel to the mine storage bin, which has a capacity of 1200 tons. The bin is covered with 30-lb. rails, spaced 10 inches apart. Oversized pieces are broken by sledge hammer. Ore from the bin is fed on a conveyor by six feed-gates, then to a 48-inch trommel, where it is screened to pass a 23-inch ring, the oversize going to a No. 6 Gates gyratory crusher, and through-size being conveyed to the railroad storage bin which has a capacity of 700 tons. Through-size from the gyratory crusher goes to a 42-inch trommel, the oversize going to a picking belt, where high-grade chalcopyrite is sorted out for shipment direct to the company's smelter at Martinez. Through-size is elevated to a distributing conveyor, which carries the ore to the railroad