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Gold Look-Alikes: Pyrite, Chalcopyrite, Mica or Real Gold?

A yellow metallic flash can come from native gold, pyrite, chalcopyrite, or weathered mica—the three common look-alikes identified by the U.S. Geological Survey. Colour and sparkle are only starting clues. Native gold is unusually dense, soft, and malleable; a suitable loose grain tends to dent or flatten. Pyrite is harder and brittle, chalcopyrite is softer but still brittle and often tarnished, and mica separates into thin flexible sheets. Use several observations, preserve representative material, and treat any economic conclusion as a sampling-and-assay question. Examine several grains with a hand lens in diffuse light. Record cubes or striated faces, massive brassy grains, peeling sheets, or irregular flattened metal rather than selecting only the brightest speck. Rotate the specimen. Strong flashes that switch on and off across many flat, parallel flakes support mica; consistent metallic grains without sheet edges require the next tests. On a loose, expendable grain and only where testing is permitted, press gently with a steel point. Gold tends to gouge, dent, or flatten; pyrite and chalcopyrite tend to powder, crumble, or fracture; mica may flex, peel, or split into sheets. Use a streak plate only on expendable material that is safe to test. Gold leaves a yellow streak, pyrite and chalcopyrite leave dark green to black streaks, and common mica leaves a white streak. Add hardness and tarnish evidence. Pyrite is hard enough to scratch glass, chalcopyrite is softer and may show blue, purple, or green iridescent tarnish, while pure gold is about Mohs 2.5 to 3. Use heft only when comparable volumes are available. Native gold is far denser than the common look-alikes, but tiny flakes, attached host rock, and mixed grains make hand-heft judgments unreliable. If the occurrence could matter, document the geology and location, retain representative samples under the applicable collecting rules, and use a qualified laboratory assay. A visible speck cannot establish grade, tonnage, ownership, or value. Do not call a specimen gold from colour, glitter, a phone photo, or one positive-looking test. Gold and its look-alikes can occur together, and weathering changes surface appearance. Do not crush, grind, drill, heat, acid-test, or flame-test unknown sulfide material. Avoid dust, wear appropriate protection for authorized work, and wash hands after handling field s

  • Pyrite vs Gold — Compare hardness, crystal form, streak, brittleness, and deformation.
  • Chalcopyrite vs Gold — Compare tarnish, dark streak, brittleness, density, and colour.
  • Mica vs Gold — Compare sheet cleavage, flexibility, changing reflections, streak, and heft.

Verification resources

Cross-check terminology, classification, methods, and safety with these authoritative external resources.

  • What is Fool's Gold? — U.S. Geological Survey. Names pyrite, chalcopyrite, and weathered mica as common gold look-alikes and compares deformation and streak.
  • Chalcopyrite — University of Minnesota. Documents brass colour, dark streak, hardness, brittleness, tarnish, density, occurrence, and comparison with gold.
  • Pyrite — University of Minnesota. Documents pyrite hardness, brittle behaviour, crystal forms, and distinctions from chalcopyrite and gold.
  • Gold — Geoscience Australia. Summarizes native gold's yellow colour, Mohs hardness, density, malleability, ductility, occurrence, and uses.

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