Meadow Lake (Excelsior)

Site Name

Primary: Meadow Lake (Excelsior)

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Commodity

Primary: Gold
Secondary: Silver
Tertiary: Copper
Tertiary: Lead
Tertiary: Iron
Tertiary: Zinc

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Location

State: California
County: Nevada
District: Meadow Lake District

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Land Status

Land ownership: National Forest
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: Tahoe National Forest (U.S. Forest Service)

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Holdings

Not available

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Workings

Not available

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Ownership

Not available

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Production

Not available

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Deposit

Record Type: District
Operation Category: Past Producer
Deposit Type: Hydrothermal vein
Operation Type: Surface-Underground
Discovery Year: 1863
Years of Production:
Organization:
Significant: Y

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Physiography

Not available

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Mineral Deposit Model

Model Name: Low-sulfide Au-quartz vein

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Orebody

Form: Tabular, lens

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Structure

Not available

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Alterations

Alteration Type: L
Alteration Text: Intense alteration by segregation or replacement in granitic - granodioritic country rock. Alteration characterized by bluish quartz, black tourmaline (tourmalinization), epidote, calcite, and other minor gangue minerals

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Rocks

Name: Granite
Role: Host
Age Type: Host Rock
Age Young: Cretaceous
Age Old: Jurassic

Name: Granodiorite
Role: Host
Age Type: Host Rock
Age Young: Cretaceous
Age Old: Jurassic

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Analytical Data

Not available

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Materials

Ore: Gold
Ore: Quartz
Ore: Tourmaline
Ore: Epidote
Ore: Calcite
Gangue: Granite

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Comments

Comment (Deposit): The Meadow Lake District produced free gold from shallow oxidized surface deposits and auriferous metallic sulfides contained in the deeper unoxidized quartz veins. Lindgren (1897) characterized the deposits as hypothermal fracture-filling gold-quartz veins. However, the marked dissimilarity of the veins from typical California quartz veins caused Wisker (1936) to classify them as transitional deposits between gold-quartz deposits and copper tourmaline deposits since they exhibited qualities of both. Unlike typical California low-sulfide free-milling gold-quartz veins, the veins do not contain native gold. Free gold only occurs in a thin oxidized zone in which the gold has been liberated from auriferous sulfides by weathering. In the deeper unweatherd vein, gold occurs only in an unusually high content of auriferous sulfides. Sulfides run 10-20%; pyrite is the most abundant, but with considerable chalcopyrite, arsenopyrite, galena, and sphalerite. The abundant sulfides caused the exposed vein to develop a black or rusty stained gossan cap, with small bunches of ore containing as much as 30% copper. Resistance of the sulfides to amalgamation was largely responsible for the district's short and disappointing history. Another characteristic differing from the typical California quartz vein is the absence of well defined walls. Much of what appears to be vein material is highly altered country rock that contains bluish quartz, black tourmaline, epidote, calcite, other minor gangue minerals, and a high iron content.

Comment (Development): Gold was first discovered in 1863 by Henry H. Hartley, on claims that became the Excelsior Mine. The discovery inspired a short rush to the district between 1863 to 1866 during which seven quartz mills were built. The town of Meadow Lake (Summit City) was incorporated in 1866 and quickly grew to as many as 5,000 residents. Logan (1924) reported that by 1865, 1200 locations were made and that in 1866 400 houses were built in the town. In the five years that the district was most active (1865-1870), thousands of feet of shallow workings on many different claims were run (cuts, shafts drifts, and tunnels) and every observed showing of rich oxidized ore was mined out. When the shallow oxidized ore played out and the sulfide ores were reached, the town was quickly abandoned. By 1877 only 25 residents remained in Meadow Lake. By the early 1870s, Hartley's Excelsior Mine was the only mine still operating and making a moderate profit by concentrating on the shallow oxidized to semi-oxidized zones. Due to the mines location in the High Sierra, heavy winter snows prevented winter operation. It could only be operated in the summer, with supplies being hauled in from Emigrant Gap. By 1888, the mine had a ten-stamp mill, which used the Morris process for recovering the gold. The mill had no plates; instead the pulp was run over a large canvas with strips of wood fastened lengthwise on it. The heavier material was removed and put in an amalgamation tub. Recovery from the ore was running $6.00 per ton. The sulfides were not abundant enough to warrant their recovery. In 1892, Hartley was murdered and his wife gained control of the mine, which she later sold shortly before her death. The last run from the original Excelsior Mine was in 1905, in which the recovery was reported as $10.14 per ton from 266 tons of ore. By 1915, the mine was again in operation, albeit briefly, by the Excelsior Consolidated Mining Company. At this time, the Excelsior Mine consisted of four patented claims, the Excelsior No. 1, Excelsior No. 1, Union No. 1 and Union No. 2. A new boarding house was erected in 1914 and a new mill and pipeline built in 1915. By December 1915, a second unit of 3 stamps was added to the mill and a third was being constructed. Operations quickly came to an end, and by 1918 the mine was idle. Wisker (1936) noted that most records from the years of peak activity (1865-1872) were not preserved, and records made during the last period of mine operation at the Excelsior Mine were burned in a fire at the mine subsequent to 1915. Minor prospecting was again done in the 1920s and 1930s, but by 1924 the district was practically deserted. Despite the occurrence of abundant auriferous sulfides (15-20%) in the ores, their resistance to amalgamation repeatedly defeated the efforts of the early miners to extract substantial values that were often shown by assays. Metallurgists of the day could not profitably extract the gold from the sulfides. Alternative methods, such as roasting or chlorination were prohibitively expensive, and the ores were usually too low grade for shipment of concentrates to far off smelters. The primitive quartz mills, and the several arastras, treated the ores of the shallow oxidized zones (15 to 40 feet deep) with a reasonable degree of success, but failed as the sulfides were encountered. One after another, the miners quit and moved on.

Comment (Economic Factors): The entire Meadow Lake District produced an estimated $200,000, most of which came from the Excelsior Mine. The best ores were the very shallow oxidized surface ores, which yielded free gold and weathered auriferous sulfides. Unweathered ore contained no free gold and consisted of low-grade quartz with auriferous sulfides, concentrates of which were more often unprofitable. The richest oxidized ores generally yielded between $13.00 and $98.00 per ton, but one run of high grade ore from the Excelsior assayed $411.50 per ton (Wisker, 1936). Reported average ore values generally ranged between $6 to $10/ton ($20.67 gold).

Comment (Commodity): Ore Materials: Free milling gold in shallow oxidized zone and auriferous sulfides in unoxidized vein material

Comment (Commodity): Gangue Materials: Granodiorite, granite, quartz, tourmaline, epidote, calcite

Comment (Geology): REGIONAL GEOLOGY The northern Sierra Nevada basement complex has a history of both oceanic and continental margin tectonics recorded in sequences of oceanic, near continental, and continental volcanism. The complex has been divided into four lithotectonic belts; the Western Belt, Central Belt, Feather River Peridotite Belt, and Eastern Belt. The Western Belt is composed of the Smartville Complex, an Upper Jurassic volcanic-arc complex consisting of basaltic to intermediate pillow flows overlain by pyroclastic and volcanoclastic rocks with diabase, metagabbro, and gabbro-diorite intrusives. To the east it is bounded by the Big Bend-Wolf Creek Fault Zone. East of the Big Bend-Wolf Creek Fault Zone is the Central Belt, which is in turn bounded to the east by the Goodyears Creek Fault. This belt is structurally and stratigraphically complex and consists of Permian-Triassic argillite, slate, chert, ophiolite, and greenstone of marine origin. The Feather River Peridotite Belt is also fault-bounded, separating the Central Belt from the rocks of the Eastern Belt for almost 95 miles along the northern Sierra Nevada. It consists largely of Devonian-to-Triassic serpentinized peridotite. The Eastern Belt, or Northern Sierra Terrane, is separated from the Feather River Peridotite Belt by the Melones Fault Zone. The Northern Sierra Terrane is primarily composed of siliciclastic marine metasedimentary rocks of the Lower Paleozoic Shoo Fly Complex overlain by Devonian-to-Jurassic metavolcanic rocks. Farther east are Mesozoic granitic rocks of the Sierra Nevada Batholith. LOCAL GEOLOGY Given the district's location in the higher elevations of the Sierra Nevada, Pleistocene glaciation has stripped away the Tertiary volcanic cover exposing Mesozoic bedrock of the Sierra Nevada Batholith. Bedrock is chiefly Jurassic - Cretaceous diorite, granite, and granodiorite, which intruded Eastern Belt shale and slate of the Sailor Canyon Formation. Remnants of Sailor Canyon Formation rocks occur within the intrusives and are strongly metamorphosed near their igneous contacts. The veins occur within granite and granodiorite bedrock. There are two major vein systems. The main system includes the thick (50-foot wide) Excelsior vein and has a general strike of N 25? - 30? W. The more numerous and smaller veins of the other system (2 -15 feet wide) vary between N 45? W and N 85? W. The general dip of all veins is to the southwest at angles from 50? to 80?. The principal veins occupy fissures and show evidence of post-emplacement movement within the veins (brecciation and slickensiding) and of abundant alteration, replacement, and silicification of original gangue material. The main Excelsior vein is a prominent vein striking N 30? W and dipping 50? southwest within granodiorite walls. It averages 45 feet thick, but in places the outcrop is as much as 100 feet wide. The central portion of the vein is of quartz at least 15 feet thick. About 300 feet to the northeast is a strong parallel vein 5 to 9 feet wide.

Comment (Geology): The Meadow Lake veins differ markedly from the typical gold quartz veins of the Sierra Nevada. They contain much less quartz and an unusually high metallic sulfide content. They don't have well defined walls, which indicates segregation or replacement. In many cases, much of what appears to be vein material itself is highly altered and silicified country rock with bluish quartz, black tourmaline, epidote, calcite, other minor gangue minerals, and a high iron content. Unlike the typical white quartz veins, the veins exhibit gossan outcrops with the exposures generally black or rusty from oxidation of the sulfides. In many places along the outcrop copper sulfides occur, in amounts varying from a trace to small bunches of ore containing as much as 30% copper. The oxidized zone weathers faster than the surrounding country rock, and the veins are traceable on the surface by a depression rather than a resistant outcrop. Lindgren (1897) classified the Meadow Lake ore deposits as hypothermal fissure veins. Wisker (1936) describes them as a transitional type between gold-quartz and copper-tourmaline deposits as they exhibit qualities of both. Free gold occurs only in the shallow oxidized zone where most of the early workings were restricted to only a few hundred feet. A number of near-surface high-grade pockets were found in the oxidized zone, but these quickly pinched out or became very low grade with depth. Most attempts to exploit the veins failed owing to their low grade and absence of free gold. The veins themselves generally contain from 10 to 20% auriferous sulfides. The quartz in the veins contains no free gold and is generally barren. The sulfides are principally pyrite (up to 95% of the sulfides) with some galena, sphalerite, arsenopyrite, traces of copper and some magnetite. In some veins arsenopyrite and chalcopyrite are abundant. The greatest gold values occur in conjunction with pyrite, chalcopyrite, and arsenopyrite, and the least in sphalerite and galena. Silver is negligible in the pyrite ores, but ranges from 2-15 ounces/ton in the chalcopyrite ores and 6-30 ounces/ton in the galena ores. Mill tests of the ore gave an average of $7 a ton by amalgamation, with some results reported as high as $12 a ton. The concentrates were considered very low grade given the sulfides resistance to amalgamation. The early mill had no plates, the pulp being run over canvas with wooden baffles and the concentrates then being amalgamated in a tub.

Comment (Identification): The Meadow Lake District is a small lode district in eastern Nevada County just south of Meadow Lake and approximately 7 miles northeast of the town of Cisco. While the district includes a number of small mines and claims, the Excelsior Mine produced most of the district's gold and is thought to be the only profitable mine in the district. Hence, the Excelsior Mine is sometimes considered synonymous with the Meadow Lake district. Later references to the mine include the consolidation of most of the early claims on which nine small separate mines operated during the early days. These claims include the Excelsior 1, Excelsior 2, Union 1, Union 2, of What No.1, of What No. 2, Wotell, Lake, Blue Fox, New Hope, Mammoth, North Mammoth, Dam End, Fraction, Great Eastern, Great Western, Great Western Extension, and C.B.C. (Wisker, 1936). Most of the Meadow Lake District operations were small workings that consisted of little more than a 100 foot shaft or short tunnel before being abandoned. Many of these encountered shallow high-grade ore pockets in the near-surface oxidized zone, but found that the deposits pinched out quickly or become very low grade at depth. The thin oxidized zone, low grade of the deeper ore, and the district's remote location kept production low. In total, it is estimated the district produced only $200,000 (Clark, 1970). Due to the relative obscurity of this district relative to other lode gold districts in the Sierra Nevada, there is scant information regarding the mines or detailed geology.

Comment (Location): Location selected for latitude and longitude is the Excelsior Mine shaft symbol on the USGS 7-1/2-minute English Mountain quadrangle

Comment (Workings): Logan (1924) described the mine workings after its last period of operation. Development consisted of a shaft 180 feet deep on the dip of the Excelsior vein, with levels at 60 feet and 120 feet. The first level was drifted southeast 300 feet, and from the second level ore was stoped and milled for a length of 40 feet to the surface, just northwest of the shaft. The surface plant included a mill with rock breaker, 10 stamps and plates, 9 small cyanide tanks, and a machine shop. Power was furnished by water brought through 4,700 feet of pipe from Meadow Lake. The last operator was the Excelsior Consolidated Gold Mining Company.

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References

Reference (Deposit): Clark, W.B., 1970, Gold districts of California: California Division of Mines and Geology Bulletin 193, p. 89.

Reference (Deposit): Crawford, J.J., 1896, Nevada County, Excelsior Mine: California State Mining Bureau Report 13, p. 243.

Reference (Deposit): Irelan, W., Jr., 1888, Nevada County, Meadow Lake district: California State Mining Bureau Report 8, p. 454.

Reference (Deposit): Lindgren, W., 1897, Truckee folio, California: U.S. Geological Survey Atlas of the U.S., Folio 39, 8 p.

Reference (Deposit): Lindgren, W., 1900, Colfax folio, California: U.S. Geological Survey Atlas of the U.S., Folio 66, 10 p.

Reference (Deposit): Logan, C.A., 1924, Nevada County, Meadow Lake district: California State Mining Bureau Report 20, p. 355-362.

Reference (Deposit): MacBoyle, E., 1919, Nevada County, Meadow Lake district, Excelsior Mine: California State Mining Bureau Report 16, p. 33-37, 168.

Reference (Deposit): Wisker, A. L., 1936, The gold-bearing veins of the Meadow Lake district, Nevada County: California Journal of Geology, v. 32, p. 189-204.

Reference (Deposit): Additional information on the Meadow Lake District is contained in File No. 331-9362 (CGS Mineral Resources Files, Sacramento)

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