Porphyry copper deposit

A large, low- to medium-grade copper ore deposit formed when hydrothermal fluids associated with shallow, porphyritic igneous intrusions concentrate copper and related metals.

Hydrothermal alteration: Chemical and mineralogical changes in rocks caused by hot, reactive fluids. Fluid-driven alteration halos reveal the pathways and changing chemistry around the intrusion.
Chalcopyrite: A copper iron sulfide mineral and the principal copper ore in many deposits. It is commonly the main copper-bearing sulfide in porphyry ore.
Porphyry copper exploration: The search for copper deposits using geological, geochemical, and geophysical evidence. Alteration patterns and intrusive rocks help explorers identify concealed porphyry systems.
Bingham Canyon Mine: A major porphyry copper mine in Utah, United States. Its immense open pit illustrates the scale possible in a porphyry system.
Potassic alteration: A hydrothermal alteration assemblage commonly marked by potassium feldspar and biotite. It commonly forms near the center of porphyry systems and accompanies early copper mineralization.
Bornite: A copper iron sulfide mineral known for its iridescent tarnish and high copper content. It can contribute higher-grade copper zones within the larger, lower-grade system.
Induced polarization: A geophysical method that measures how subsurface materials temporarily store electrical charge. Disseminated sulfides can produce chargeability anomalies that help locate buried mineralization.
Escondida mine: A large copper mine in the Atacama Desert of northern Chile. It is a major operating example of a copper-rich porphyry deposit.
Phyllic alteration: Hydrothermal alteration dominated by quartz, sericite, and pyrite. Its broad, pyrite-rich zones commonly overprint earlier alteration around porphyry centers.
Molybdenite: A molybdenum sulfide mineral that commonly occurs in porphyry systems. Its presence can make molybdenum a significant coproduct alongside copper.

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