Beebe Mine (Iowa claim; Woodside-Eureka claim; Brooklyn claim; East Lode claim), Georgetown, Georgetown District, East Segment Mother Lode, El Dorado County, California, USAi

Regional Level Types
Beebe Mine (Iowa claim; Woodside-Eureka claim; Brooklyn claim; East Lode claim)	Mine
Georgetown	Census-designated Place
Georgetown District	Mining District
East Segment Mother Lode	Lode
El Dorado County	County
California	State
USA	Country

A former lode Au-Ag mine located in secs. 2, 3 & in the NW center sec. 11, T12N, R10E, MDM, 0.5 km (0.3 mile) NNE of Georgetown proper, on private land. Discovered in 1848. Operated by the Woodside-Eureka Mining Co., Ltd. Production years were 1932 to 1939. MRDS database stated accuracy for this location is 100 meters.

The Beebe Mine is located within the Georgetown District in northwestern El Dorado County at the northeast end of the Mother lode Gold belt. The Beebe Mine includes neighboring leases and mines (including the Woodside-Eureka Mine and the Brooklyn, East Lode, Iowa claims), some of which were worked independently before their consolidation with the Beebe Mine in 1932. The mine is considered one of the larger gold producers in El Dorado County having produced an estimated $2 million from several replacement "veins" within amphibolite schist of the Paleozoic-Mesozoic Calaveras Complex.

This mine is a consolidation of as number of claims and was once one of the larger sources of gold in the county. The location of the claims is shown on Pl. II, Logan (1938). There are apparently 2 seaprate groups of claims per the locations shown in Logan (1934).

The Woodside-Eureka Mine, which worked its namesake claims, was discovered in 1848 and was worked from 1848 to about 1900. Little information is available about the independent operations of the Woodside-Eureka Mine. By 1866, it was opened to a depth of 110 feet and by 1867 to a depth of 210 feet. In 1867, it had a 5 stamp mill and had produced considerable "high grade" ore. It was reopened by the Woodside-Eureka Company in 1906 who proceeded to unwater the Eureka Shaft. The mine was again idled in 1908. By that time, the deeper shaft was sunk to 240 feet with levels at 85 feet and 200 feet. On the 200 foot level, short drifts were run north and south. Another old shaft was reportedly 180 feet deep (Logan, 1934). Considerable water was reported in the Woodside workings and this was given as the main reason for stopping work (Logan, 1934).

The Beebe claim itself was prospected in 1917 to a depth of 250 feet, but remained unworked thereafter until 1931, when Alexander Wise took it over. The Beebe Gold Mining Company was formed to develop the property and adjoining claims, and a plant was built containing two Hadsell mills and cyaniding equipment. Mining had been going on only a short time when Wise died and the property was taken over by the Pacific Mining Company (Logan, 1934). By 1938, the Hadsell mills had been replaced by two 7 foot by 36 inch Hardinage conical ball mills. Overflow from the classifier below the ball mills passed to 24 Kraut flotation cells. The concentrate from these was thickened to 50% solids, ground in a 5 foot by 8 foot Marcy mill and treated with cyanide in two 30 foot by 8 foot Devereaux agitators. After passing through 3 thickeners, the pregnant solution was filtered and the gold precipitated by zinc dust (Logan, 1938). From 1932 until 1939, the Beebe Gold Mining Company operated the mine and removed 306,241 tons of ore that produced $1,200,465 in gold. A crew of about 45 men were employed at mine by 1934 and the mine was were producing and milling 325 tons a day. This high efficiency resulted in a low mining cost reported to be $1.17 per ton and allowed the working of the generally low grade Beebe ore (Logan, 1934).

By 1934, the Pacific Mining Company had extended the Beebe 250 foot level under the Eureka and have sunk a winze to the 500 foot level on the Eureka vein (Logan, 1934). Ore had been stoped in the Eureka to 130 feet in depth but the output from this is not definitely known. By 1938, a new shaft in the vein had been raised from the 500 foot level to the surface about 190 feet from the old one. A winze has been sunk 200 feet from the 500 foot level at a point 500 feet northeast of the main shaft and by July, 1938, ore was being stoped from the 600 foot level in the Eureka claim. A length from 500 to 600 feet along the strike was worked from the surface to a depth of 250 feet. On the 370 foot level, a length of about 700 feet was drifted in ore, of which 65% was mined, the balance being left in pillars. The stoped width varied from 5 feet to 50 feet and averaged 12-15 feet (Logan (1938)). The Mine was closed in 1939. After 1939, a little gold was found while cleaning up.

Mineralization is a vein deposit (Mineral occurrence model information: Model code: 273; USGS model code: 36a; Deposit model name: Low-sulfide Au-quartz vein; Mark3 model number: 27) hosted in amphibolite, diorite, slate and schist. Unlike typical Mother Lode fracture filling quartz veins, the principle ore bodies in the Beebe Mine consisted of zones of replacement and silicification of amphibolite wallrock that resembled conventional fissure filling veins. The ore body is tabular in form, strikes NE and dips 80SE at a thickness of 15.24 meters. The Beebe-Eureka vein is a silicified and mineralized zone in schist from 5 to 50 feet thick with an average width of 12 to 15 feet. On the footwall of one zone there is a diorite dike 1 to 2 feet in width. A number of narrow, basic dikes are also within the ore zone. Controls for ore emplacement included replacement along a fracture conduit. Ore materials include free-milling gold and auriferous sulfides. Gangue materials include quartz, calcite, and amphibolite schist. Local alteration included the silicification of the amphibolite schist. Local rocks include Jurassic marine rocks, unit 1 (Western Sierra Nevada and Western Klamath Mountains).

The Beebe "vein" is a silicified and mineralized zone of sericite and chloritic amphibolite schist within the Calaveras Complex. It strikes about N 20? E and dips 70?-80? east. Hydrothermal fluids migrating along a fracture resulted in the replacement and silicification of the amphibolite schist hanging wall into a gradational zone of light colored sericite quartz schist bearing free gold and auriferous pyrite having a width of 5-50 feet but averaging 25 feet wide. Further silicification converted the rock into a white, fine granular replacement quartz vein with plentiful cubes of distributed pyrite that characterizes the best ore (Hershey, 1934, unpublished geological report). Replacement, silicification, and gold values diminish with distance from the footwall. On the footwall is an unmineralized, but highly altered basic dike 10 inches to 2 feet wide, which forms a convenient footwall to the stopes of the Beebe vein (Hershey, 1934, unpublished geological report). Underlying the dike, footwall amphibolite is unmineralized. Ore from the Beebe vein was low grade and high in sulfides, carrying a reported 6.5% sulfides. Discussion of specific ore shoots is contained in an unpublished geologic report of the Beebe Mine contained in the files of the California Geological Survey Mineral Resource file No. 331-9748.

The Eureka "vein" or orebody is also composed of a zone of replacement within amphibolite schist. The orebody is more perfectly silicified than other material in the vicinity and has coarser pyrite cubes that are more evenly spaced than in neighboring orebodies. The ore body is triangular in cross section, and terminated on the north by a vertical gouge seam, against which it is nearly 50 feet wide. About 120 feet south, it tapers to a point where the mineralized rock practically pinches out in green schist. The Eureka vein produced a somewhat higher average grade of ore than the Beebe vein.

Ore was reported to average 0.24 oz per ton.

Little information is available regarding the Woodside vein. The vein was reported to be 2 or 3 feet wide and enclosed in black Mariposa Formation slate. It was a producer of specimen ore in the early days and one wheelbarrow load of especially high-grade specimen material was reportedly worth $12,000 (Logan, 1934). Reported average values for milling ore vary widely ranging from $3 - $63.80 per ton (period values).

Local and regional geologic structures include the Melones Fault Zone.

Workings include underground openings comprised of 3 shafts (Eureka, Old Beebe and the Beebe No. 2) up to 700 feet deep with 6 levels (130, 250, 320, 500, 600 & 700 feet) and extensive drifting, stoping and other workings, including a winze between the 500 and 700 foot levels. The shrinkage stope mining method was employed. A schematic (longitudinal projection) of the underground workings and stoped areas of the Beebe Mine is given by Clark and Carlson (1956) (Figure 16, page 407).

No information is readily available regarding production from the Woodside-Eureka claims between their discovery in 1848 and their consolidation with the Beebe mine in 1931. During operation of the Beebe Mine by the Beebe Mining Company, from 1932 until 1939, the property produced $1,200,465 (period values) from 306,341 tons of ore. After 1939 only a small amount of gold was produced from cleanup operations.

Ore from the Beebe vein was low grade and high in sulfides, carrying a reported 6.5% sulfides. The Eureka vein produced a somewhat higher average grade of ore than the Beebe vein, with ore reportedly averaging about 0.24 ounces of gold per ton. Reported average values for milling ore from the Woodside vein vary widely ranging from $3 - $63.80 per ton (period values), with a wheelbarrow full of high grade specimen ore commanding $12,000.

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Link to USGS MRDS:	10006974

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References