Pyrite is iron sulfide, the most abundant sulfide mineral on Earth, and the most famous impostor in collecting history. Brass-yellow, heavy, and satisfying to hold, it dazzles until you check three things: streak, brittleness, and crystal faces. Real gold is soft, ductile, and streaks yellow. Pyrite streaks greenish-black, shatters when struck, and shows sharp cubic faces with telltale striations. Found in quartz veins, sedimentary rock, and metamorphic schists worldwide.
Field identification workflow
- Color and luster: pale brass-yellow and aggressively metallic. Real gold is deeper yellow, and soft.
- Streak greenish-black to brownish-black — gold streaks gold. This single test has saved more dignity than any other in the library.
- Hardness 6–6.5: pyrite scratches glass; a knife will not mark it. Gold cuts like lead.
- Look for striated cube faces and brittle fracture. Gold bends; pyrite shatters.
The deceiver's companions
Pyrite anchors a vein assemblage that includes two other classic misdirections: sphalerite, the "blende" that looks like ore and yields no lead, and galena, the lead ore whose weight gives it away. Learn the trio together and hydrothermal hand specimens stop being mysterious.