Wüstite in a hydrothermal silver-lead-zinc vein, Lucky Friday mine, Coeur d’Alene mining district, U.S.A.
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Abstract
The Coeur d’Alene mining district of northern Idaho is one of the major Ag-Pb-Zn producers in the world; it contains Ag-Pb-Zn replacement veins in clastic burial metamorphic rocks of the Middle Proterozoic Belt Supergroup. Electron microprobe analyses and Raman spectroscopy of samples from the Gold Hunter vein of the Lucky Friday mine revealed the presence of the rare iron oxide wüstite (Fe1-xO) coexisting with stable magnetite. An assemblage of galena, pyrite, and siderite is associated with the two iron oxides although these minerals do not share phase boundaries with wüstite and their coexistence is, therefore, thermodynamically precluded. Wüstite is stable under high-temperature conditions (above 570°C at 1 bar). Increasing pressure can lower this temperature significantly. However, the veins in the Coeur d’Alene district formed well outside the wüstite stability field and represent a low-temperature (250-350 °C), low-pressure (1-3 kbars), and low-fO₂ environment. To form wüstite at temperatures around 250-350°C a pressure increase of at least 70 kbars would be required. This corresponds to burial of around 250 km, which is geologically unrealistic. Similarly, to form wüstite, the temperature must have exceeded 570°C, which exceeds the maximum temperatures of vein formation by at least 200 °C. A temperature increase of that scale is not reflected in the mineral assemblage of the veins or the host rocks, which both contain siderite. We conclude that wüstite formed as a metastable phase at 250-350 °C and pressures below 100 bars because of the low-fO₂ conditions in the Coeur d’Alene district
© 2015 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Paulscherrerite from the Number 2 Workings, Mount Painter Inlier, Northern Flinders Ranges, South Australia: “Dehydrated schoepite” is a mineral after all
- Atomistic investigation of the pyrophyllitic substitution and implications on clay stability
- Application of the two-feldspar geothermometer to ultrahigh-temperature (UHT) rocks in the Khondalite belt, North China craton and its implications
- Wüstite in a hydrothermal silver-lead-zinc vein, Lucky Friday mine, Coeur d’Alene mining district, U.S.A.
- Gelosaite, BiMo6+(2–5x)Mo5+6xO7(OH)·H2O (0 ≤ x ≤ 0.4), a new mineral from Su Senargiu (CA), Sardinia, Italy, and a second occurrence from Kingsgate, New England, Australia
- Improved electron probe microanalysis of trace elements in quartz
- Ultra-high residual compressive stress (>2 GPa) in a very small volume (<1 μm3) of indented quartz
- Transmission electron microscopy investigation of Ag-free lillianite and heyrovskýite from Vulcano, Aeolian Islands, Italy
- Combined inelastic neutron scattering and solid-state density functional theory study of dynamics of hydrogen atoms in muscovite 2M1
- Contact metamorphism of a Cretaceous accretionary prism by the 14 Ma Okueyama granite, a single post-kinematic pluton in Central Kyushu, Japan: SVD analysis of metamorphic reactions and thermal release
- Origin of crosscutting dissolution surfaces in magmatic plagioclase
- Néel transition in (Mg,Fe)O: A possible change of magnetic structure
- Extreme channelization of fluid and the problem of element mobility during Barrovian metamorphism
- The high-temperature P21/m → C2/m phase transitions in synthetic amphiboles along the richterite–(BMg)–richterite join
- The crystal structure of barite, BaSO4, at high pressure
- Thermal decomposition of brushite, CaHPO4·2H2O to monetite CaHPO4 and the formation of an amorphous phase
- Rhombic-shaped nanodomains in columbite driven by contrasting cation order
- High-pressure structural evolution and equation of state of analbite
- In-situ dehydration studies of fully K-, Rb-, and Cs-exchanged natrolites
- The crystal structures and Raman spectra of aravaipaite and calcioaravaipaite
- Temperature dependence of the Fe2+ Mössbauer parameters in triphylite (LiFePO4)
- Synthesis and characterization of françoisite-(Nd): Nd[(UO2)3O(OH)(PO4)2]·6H2O
- Fluorphosphohedyphane, Ca2Pb3(PO4)3F, the first apatite supergroup mineral with essential Pb and F
- A new mineral with an olivine structure and pyroxene composition in the shock-induced melt veins of Tenham L6 chondrite
- The WURM project—a freely available web-based repository of computed physical data for minerals
- Acid production by FeSO4·nH2O dissolution: Comment
- Letter. Crystal chemistry of sodium in the Earth’s interior: The structure of Na2MgSi5O12 synthesized at 17.5 GPa and 1700 °C
- Letter. In-situ infrared spectra of OH in olivine to 1100°C
