Indikatormineral

Indikatormineral, or indicator mineral, is a mineral whose occurrence, abundance, or chemical composition signals particular geological conditions, most often the potential presence of an ore deposit or a specific metamorphic or magmatic process. Indicator minerals are typically not the ore minerals themselves; instead they reflect the nature of the source rock, the transport history of sediments, or the conditioning of fluids that may concentrate ore.

In mineral exploration, geologists search for indicator minerals in soils, stream sediments, and heavy-mineral concentrates. The presence and assemblage of indicator minerals, along with their concentrations and chemical signatures, help delineate prospective zones and guide drilling. Indicator mineral methods are used worldwide across various deposit types, including diamond, gold, and porphyry copper systems.

Representative indicator minerals by deposit type include: for diamonds—chromian spinel, garnet (pyrope), and picroilmenite; for gold—arsenopyrite and pyrite; for nickel-copper sulfide deposits—pentlandite and pyrrhotite; magnetite can be an indicator in some copper-porphyry districts. These minerals may originate far from the ore body and be transported by water or ice, but their modal abundance and chemistry point toward favorable source regions.

While useful, indicator minerals are not definitive proofs of ore. They provide targets for investigation, not confirmations. Reliable interpretation requires integrated geological mapping, geochemistry, geophysics, and, ultimately, drilling.