Mount Hope mine, Mount Hope Mining District, Eureka County, Nevada, USAi

Regional Level Types
Mount Hope mine	Mine
Mount Hope Mining District	Mining District
Eureka County	County
Nevada	State
USA	Country

Replacement deposit.

Structure: Roberts Mountains Thrust Fault host rocks in the deposit area are cut by several faults: the N35W-trending Ravine Fault, the N60W-trending Bisoni Fault, the N80W-trending Tia Fault, and the N75W-trending South Fault. The Mount hope Fault is arcuate, changing orientation dramatically from about N30E north of the mine area to N75W south of the mine area, with the bend in the fault occurring in the vicinity of the molybdenum deposit.

Alteration: Skarn development, tactite-hornfels at the historic lead zinc deposits. The porphyry molybdenum deposit is characterized by a variety of alteration assemblages attendant upon the mineralization. These include argillic-propylitic, argillic, potassic-phyllic, potassic, silica-flooded, and biotite zones, roughly concentrically zoned outward from the core of the hydrothermal system.

Commodity: Ore Materials: molybdenite, bornite, marmatite, blackjack, galena, pyrrhotite, chalcopyrite; Gangue Materials: garnet, diopside, quartz, tremolite, calcite, pyrite, magnetite, hematite.

Deposit: Ore deposits occur near the contact of an alaskite stock with the carbonate rocks it intrudes. Ore of the historic lead-zinc deposits occurs as replacement bodies in limestone roof pendants. Significant molybdenum mineralization is mainly confined to Vinini hornfels and several phases of quartz porphyry intrusive. The mineralization forms two adjacent inverted cone-shaped double shells.

Deposit type: Climax Mo

Development: Exploration began in the Mount Hope area in 1871 following the discovery of lead-zinc ore by charcoal producers for the Eureka and Palisade Railroad and the Eureka smelters. The district was first called MmcGarry (McGeary) but was unsuccessful and died out, later to be revived as the Mount Hope District in the mid 1880s. The Lorraine workings were opened in 1886 and local lawyer Thomas Wren sank the Mt. Hope #2 adit and Whim shaft in the early 1890s. The main periods of development at Mount Hope were from 1936-1938 and 1946-1949, when housing for the mineworkers was erected on site. The area was explored by the United States Bureau of Mines (U.S.B.M.) in 1946. Renewed exploration for molybdenum by Exxon Co., USA in the late 1970s and early 1980s outlined a sizeable porphyry molybdenum orebody of mineable grade in the Mount Hope area. In November 2004 Idaho General Mines, Inc. (IGMI) announced that an agreement had been signed with Mount Hope Mines, Inc. whereby IGMI has been granted an exclusive one-year option to lease Mount Hope's previously drilled molybdenum deposit in Eureka County, Nevada. This option to lease, exercisable by Idaho General Mines at anytime in the first year, allows IGMI to invoke a pre-negotiated 30 year (extendable) lease on the property upon exercise. The property consists of 13 patented claims and 109 unpatented claims. In addition, 350 adjoining claims have now been located and made a part of the property. IGMI has access to an extensive database of drilling and feasibility work accomplished by several major mining companies during the 1980s. The drilling of 135 diamond drill holes delineated an extensive porphyry molybdenum deposit that is geologically similar to the large molybdenum deposits at the famous Climax and Henderson Mines in Colorado. The drilling at Mount Hope identified 630 million tons grading .085 percent molybdenum. A higher-grade central area at relatively shallow depth was extensively drilled. Feasibility studies in the l980s targeted mining 205 million tons grading 0.11 percent molybdenum (2.2 pounds (ca. 1 kg) molybdenum per ton) by open pit methods to recover approximately 400 million pounds (ca. 181,437 metric tons) of molybdenum. IGMI will complete a pre-feasibility study over the next four months that targets mining this higher-grade core at over 25,000 tons per day. Metallurgical studies indicate a high recovery of the metal through conventional process.

Geology: The historic lead-zinc mine workings explore the contact between an alaskite stock with the carbonates of the Garden Valley Formation. Ore occurs as replacement deposits in limestone roof pendants. Large areas of skarn have been developed in the shales and carbonates.

Ore(s): Original lead-zinc deposit mineralization was controlled by carbonates in proximity to intrusive contact.

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Link to USGS MRDS:	10310475

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