GeoClassroom Physical Geology Historical Geology Structure Lab Mineralogy Petrology

Sulfides (& sulfosalts)

Sulfides: major ore minerals on earth - very diverse group

  • anions: S, Se, Te, As, Sb, Bi

      note that Se, Te, As, Sb, and Bi can also act as cations
      => resulting compound is a sulfosalt

  • cations: Fe, Cu, Zn, Ni, Co, Mn
      minor: Ag, Cd, Sn, Pt, Hg, Tl, Pb, Bi

  • Common occurrences:

    1. Associated with volcanic activity and hot springs

    2. ** Hydrothermal vein deposits (may be associated with continental rifting)

      Classification system (Lindgren)
      3 Types of Hydrothermal Deposits:

      1. Epithermal deposits:

          - relatively low temperature solution when precipitation occurs

          - pressure: moderate to low => not too deep

          - common minerals:

            ORES: stibnite (Sb), cinnabar (Hg), silver & silver
              sulfides, gold

            GANGUE: quartz, chalcedony, opal, calcite, aragonite,
              dolomite, fluorite

      2. Mesothermal deposits:

          - moderate temperatures: 200-300oC

          - pressure: moderate to high - deeper in crust

          - common minerals:

            ORES: sulfides of Fe, Pb, Zn, Cu, & gold veins

            GANGUE: quartz, calcite, rhodochrosite, siderite

      3. Hypothermal deposits:

          - high temperatures: 300-500oC

          - pressure: moderate to high

          - common minerals:

            ORES: cassiterite (Sn), scheelite & wolframite (W),
              molybdenite (Mo)

            GANGUE: quartz, tourmaline, topaz,

              other high temp silicates

      Supergene Enrichment

      *veins undergo a secondary enrichment - become more concentrated in ores

All Pages Copyright © GeoClassroom. All Rights Reserved.