Mercury ores from the New Idria Mining District, California: geochemical and stable isotope studies
The mercury ores of the New Idria Mining District are composed of metacinnabar and cinnabar with minor amounts of stibnite and iron disulfides. Metacinnabar from the main ore zone at the New Idria Mine contains Fe as a major impurity, whereas that from the CO veins contains both Se and Fe in solid solution. The impurity content varies within the same specimen and within individual crystals as well and demonstrates lack of chemical equilibrium. Most of the pyrite and marcasite crystallized earlier than cinnabar and in rare cases contain nuclei of framboidal pyrite. Pyrite and marcasite crystallized as discrete phases, and the latter does not show evidence of transition to pyrite. Dolomite shows normal marine carbonate delta/sup 18/O and delta/sup 13/C values. Quartz displays delta/sup 18/O ranging from 18.5 to 21.5 per thousand, distinctly lower than the associated dolomites, suggesting that the two minerals may have formed at two different stages. The range of delta/sup 34/S values for metacinnabar overlaps with that of cinnabar. The delta/sup 34/S for pyrite ranges from 3.1 to 13.0 per thousand; pyrite with framboidal nuclei shows the highest delta/sup 34/S values. The sulfur isotope data also suggest the lack of isotopic equilibrium. The source of C in the ore-forming fluids was marine carbonates leached from the Franciscan sediments. The source of S is uncertain because of lack of knowledge of the isotopic composition of total sulfur. It is likely that mixed sources of sulfur leached from sulfides in the host rocks and magmatic sulfur are involved.
- Research Organization:
- Carnegie Institution of Washington, Washington, DC (USA)
- OSTI ID:
- 6938597
- Journal Information:
- Geochim. Cosmochim. Acta; (United States), Vol. 51:6
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CINNABAR
GEOCHEMISTRY
ISOTOPE RATIO
MINERALOGY
ORE COMPOSITION
CALIFORNIA
CARBON
CHEMICAL COMPOSITION
DOLOMITE
IRON SULFIDES
MARCASITE
MERCURY
ORES
PYRITE
SULFUR
ALKALINE EARTH METAL COMPOUNDS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CHALCOGENIDES
CHEMISTRY
ELEMENTS
FEDERAL REGION IX
IRON COMPOUNDS
MAGNESIUM CARBONATES
MAGNESIUM COMPOUNDS
MERCURY COMPOUNDS
MERCURY SULFIDES
METALS
MINERALS
NONMETALS
NORTH AMERICA
OXYGEN COMPOUNDS
SULFIDE MINERALS
SULFIDES
SULFUR COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
USA
580400* - Geochemistry- (-1989)