A very large, low-grade copper system formed around an intrusion — the source of most of the world's copper.
A large, low-to-moderate grade copper deposit formed by hydrothermal fluids associated with intrusive igneous rocks. Porphyry deposits account for most global copper production and often contain significant by-products including gold, molybdenum, silver, and rhenium.
Porphyries supply the bulk of global copper because they are enormous, not because they are rich. Grades near 0.4% Cu are workable at scale, which means huge capital cost and long permitting timelines.
Judge a porphyry on tonnage, strip ratio, by-product credits and jurisdiction rather than grade. Gold and molybdenum credits often decide the economics.
A junior with a genuine porphyry discovery usually cannot build it. These are multi-billion-dollar mines, so the realistic outcome is a sale to a major.
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