Oxidation zone

The near-surface part of an ore deposit altered by oxygen-rich groundwater and weathering. It commonly contains oxidized minerals and may overlie a zone of secondary sulfide enrichment.

Weathering: The breakdown and alteration of rocks and minerals at or near Earth's surface. Surface weathering supplies oxygenated water that drives alteration in the zone.
Ore deposit: A concentration of minerals from which valuable materials can be extracted economically. The oxidation zone is the weathered upper part of an ore deposit.
Porphyry copper deposit: A large, disseminated copper deposit associated with porphyritic igneous intrusions. Its weathered profile can include copper oxides above enriched sulfide ore.
Mineral exploration: The search for economically valuable concentrations of minerals in Earth's crust. Oxidized caps can expose clues to concealed sulfide deposits.
Oxidation-reduction reaction: A chemical reaction in which electrons move between substances, changing their oxidation states. Oxidation of sulfide minerals releases dissolved metals and sulfate.
Sulfide mineral: A mineral containing sulfur combined with one or more metals or semimetals. Sulfides in primary ore are the principal minerals altered by oxidation.
Copper oxide ore: Copper-bearing ore in which copper occurs chiefly in oxidized minerals. Such minerals can form where copper sulfides weather in the oxidation zone.
Geochemical prospecting: Mineral exploration using chemical patterns in rocks, soils, sediments, or water. Metal and sulfate distributions help trace leaching from the zone.
Acid mine drainage: Acidic, metal-rich water produced when sulfide minerals oxidize and their products dissolve. Sulfide oxidation in exposed ore can generate acidic drainage.
Supergene enrichment: Secondary concentration of metals in an ore deposit through near-surface weathering and groundwater movement. Metals leached from the oxidation zone may accumulate below it.

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