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Pyrite vs Gold: How to Tell Fool’s Gold from Real Gold
Shine and yellow colour are not enough to identify visible gold. Pyrite is much harder and brittle, commonly forms striated crystals, and leaves a dark streak. Gold is soft, exceptionally dense, malleable, and leaves a yellow streak. Use several tests because both minerals can occur in the same geologic setting. Gold bends, dents, or smears under gentle pressure; pyrite chips or breaks. Gold is too soft to scratch glass and leaves a yellow streak, while pyrite commonly scratches glass and leaves a greenish-black to brownish-black streak. Inspect shape with a hand lens. Flat flakes or irregular soft-looking blebs favor gold; sharp cubes and striated faces favor pyrite. Make a streak on unglazed porcelain. A yellow streak supports gold; a dark greenish-black or brownish-black streak supports pyrite. Use an expendable piece of glass. Pyrite normally scratches it; gold does not. On a tiny inconspicuous edge, use gentle steel-point pressure. Gold deforms; pyrite breaks. Do not crush the specimen. Compare heft only after the other tests. Gold is dramatically denser, but small grains in a rock matrix are difficult to judge. Pyrite and gold can occur together. Identifying pyrite does not prove that a rock contains no microscopic gold, and visible shine does not establish economic grade. Do not use mercury, cyanide, strong acids, flame tests, or improvised chemical extraction. Economic evaluation requires proper sampling and laboratory assay. Avoid generating sulfide dust. Wash hands after handling mineralized samples and follow site-specific safety procedures.