Talapoosa mine, Talapoosa Mining District, Lyon County, Nevada, USAi

Regional Level Types
Talapoosa mine	Mine
Talapoosa Mining District	Mining District
Lyon County	County
Nevada	State
USA	Country

Gold Silver copper



Structure: The deposit occurs at the intersection of the Gooseberry-Talapoosa Lineament (a major E-W trending structural zone) and the NW-trending Bear Creek structural zone. Important mineralized structures include E-W and NW-striking high angle faults and associated fractures. NE-striking high angle faults are generally post-mineralization.

Alteration: Alteration types present are, in order of oldest to youngest: propylitic, phyllic, silicic, argillic, and opaline alterations. The pervasive propylitic assemblage consists of chlorite, zeolites, calcite, smectite clays, sodic rims on plagioclase (partial albitization), minor quartz and epidote, and trace to 2% disseminated pyrite. Magnetite is generally stable. The intensity of propylitic alteration increases with proximity to mineralized veins. Phyllic alteration is dominated by sericite and pyrite (3-5%) with lesser amounts of quartz and adularia. Celadonite and illite are also present. Phyllic alteration is generally pervasive throughout the andesite unit and the andesite breccia subunit. The silicic assemblage consists of multiple stages of banded chalcedony and drusy quartz adularia and contains minor sulfides, sulfosalts, and electrum. Quartz-adularia intergrowths commonly replace calcite cleavage planes. Silicic alteration is manifest by a well developed vein stockwork crosscutting the andesite unit, as a pervasive replacement, and as matrix to irregular zones of hydrothermal breccias. The silicic assemblage overprints both phyllic and propylitic alteration and represents the main stage of precious metal deposition. The argillic assemblage consists of montmorillonite clays, kaolinite, alunite, allophane, halloysite, jarosite, gypsum, and iron oxides. Argillic alteration is best developed in fault zones. It also occurs as a pervasive supergene product of pyrite oxidation, overprinting both phyllic and propylitic assemblages. The opaline assemblage consists of massive, multi-colored opaline-chalcedonic breccia containing iron oxides and occasional cinnabar. Opaline breccia appears to be replacing andesite tuff-breccia. The opaline breccia may represent a higher level equivalent to the silicic assemblage, deposited near the paleosurface.

Commodity: Ore Materials: electrum Gangue Materials: quartz, opal, chlorite, zeolites, calcite, smectite, epidote, pyrite, sericite, adularia, celadonite, illite, montmorillonite, kaolinite, alunite, allophane, halloysite, jarosite, gypsum, iron oxides, argentite, cinnabar.

Deposit: Gold-silver mineralization occurs in quartz stockwork veins and local sulfidic silicified breccias associated with widespread phyllic and propylitic alteration. Gold occurs as fine grained, free electrum in quartz-adularia veins, and as inclusions in, and on the surface of pyrite, argentite, and sulfosalt mineral grains. The grain size of the electrum ranges from 5-250 microns and averages 75 microns. Primary electrum is 650-850 fine. Dacite porphyry intrusions are the youngest event associated with Kate Peak volcanism, and alteration and mineralization are closely associated with porphyry emplacement.

Deposit type: Epithermal vein, Comstock

Development: Prospects in the Talapoosa district are said to have been worked in a small way as early as 1864 by prospectors from Virginia City, but with no recorded production as of 1910. It was held by the Talapoosa Mining Company from 1905 until 1925, when the company lost the property in litigation. eology and Ore Controls of Gold-Silver Mineralization in the Talapoosa Mining District, Lyon County, Nevada. In 1925, the new owners built a 50 tpd flotation mill that operated for one year, processing about 8000 tons of ore. Production was limited and sporadic in later years. Total recorded production from the district is estimated to be less than 5000 ounces of gold. Historic company records account for 22,000 tons of production. Since the 1960s, several companies have explored the district for bulk-mineable ore: Duval Corp. in 1966, Homestake Mining in 1977-78, Superior Minerals in 1978-79, and Kennecott Corp. in 1981-83. Athena Gold Corp. leased the property in 1985 and drilled 34 shallow reverse circulation drill holes. A small resource of low grade oxide mineralization was identified which was tested further by an additional 121 reverse circulation drill holes. Preliminary metallurgical tests indicated that the oxide mineralization was only moderately amenable to heap leaching. In early 1989, Athena drilled 49 reverse circulation drill holes and 5 deeper NCHQ core holes. One purpose of the reverse circulation drill holes was to provide sufficient oxide ore for bulk recovery tests. This metallurgical testing demonstrated that the oxidized ore was only marginally amenable to heap leach methods in that the ore required crushing to minus 1/4 inch to achieve reasonable cyanide extraction of the gold. However, all 5 core holes intersected thick zones of low grade sulfide mineralization. An additional 20 deep holes were drilled, resulting in the discovery of a large tabular stockwork zone (the Bear Creek zone) 300 meters wide and 750 meters long which defines the currently recognized gold-silver resource. In January, 1992, Pegasus Gold Inc. reached an agreement with Athena Gold Corp. to earn a 70% interest in the Talapoosa project. Pegasus initiated a drilling program to confirm and expand reserves and conducted metallurgical testing to determine rates of recovery. The Talapoosa Joint Venture between Athena Gold Corp. and Pegasus Gold Corp. terminated April 25, 1994 with Athena now retaining a 100% interest in the project. Miramar Mining acquired Talapoosa through a merger with Athena and continued with the permitting process and an independent feasibility study. In 1997, Miramar Mining suspended development of the Talapoosa project due in part to depressed gold prices and in part to the need for additional metallurgical testing. In June, 2002, it was reported that American Gold Capital Corp. was reactivating development at the Talapoosa property. It was still owned by American Gold Capital in 2004.

Ore(s): Mineralization is structurally controlled. Low angle fault splays in the hanging wall block of the main Talapoosa structure, and the intersection of the E-W and NW-trending structures are locally important ore controls to higher grade breccia-hosted mineralization.

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Link to USGS MRDS:	10310358

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