Pyrite is hard and brittle; gold is soft and malleable. Pyrite, often called fool’s gold, has a Mohs hardness of 6–6.5 and a greenish-black to brownish-black streak. Gold is 2.5–3 and leaves a gold-yellow streak. Those differences are more useful than a yellow sparkle, as the University of Minnesota’s pyrite reference and Cochise College’s gold reference show.
If you’re comparing pyrite vs gold in a rock you’ve found, start by locating the gold-colored grains. A test on the surrounding rock may miss those grains entirely. Keep the specimen intact while you look; you don’t need to scratch it to begin.
On this page: comparison table · what to look for · test results · common questions · observation checklist.
Pyrite vs gold at a glance
Use these reference properties to compare observations from your specimen.
| Property | Pyrite | Gold |
|---|---|---|
| Material | Iron sulfide, FeS₂ | Gold, Au |
| Surface color | Pale brassy yellow; may tarnish | Yellow to pale yellow |
| Luster | Metallic | Metallic |
| Mohs hardness | 6–6.5 | 2.5–3 |
| Streak | Greenish-black to brownish-black | Gold-yellow |
| Breakage | Brittle | Bends |
| Specific gravity | About 5 | About 19.3 for pure gold |
Sources: University of Minnesota, Cochise College and the University of California, Santa Barbara mineral key. Specific gravity compares density with water and has no units. Natural gold can contain other metals, so its specific gravity can differ from the pure-gold reference.
Look at the gold-colored grains first
Turn the specimen in ordinary light and examine the metallic areas with a hand lens if you have one. Pyrite often forms cubes or crystals with eight faces, sometimes with fine parallel lines across their faces. The University of Minnesota describes these shapes and striations. They make pyrite worth considering, but an irregular grain can still be pyrite.
Gold can form crystals too. Cochise College lists several gold crystal forms, so “it has flat faces” is not enough to rule gold out. Photograph any visible edges and lines instead of trying to break off a clearer piece.
Look at how the metallic material sits in the rock. Is it a loose grain, a patch, or scattered specks? The Kansas Geological Survey explains that rocks can contain several minerals. That matters when you interpret a test: a scratch on a pale grain beside a metallic speck describes the pale grain.
What hardness and streak results can tell you
If you already have a test result, check which material was tested before comparing it with the table.
Hardness: gold and pyrite are far apart on the Mohs scale. But a whole rock scratching glass does not identify its gold-colored specks. Quartz itself has a hardness of 7 in the UCSB mineral key, so quartz surrounding a soft grain could account for that scratch. Our Mohs hardness guide explains how to distinguish a real groove from a mark that wipes away.
Streak: a clearly identified dark mineral powder would argue against gold for the grain tested. An uncertain pale mark should stay uncertain. A hard mineral can scrape white powder from a streak plate, as the Sternberg Museum of Natural History explains. The mineral streak guide covers that problem and when to skip testing.
Scratch and streak tests leave marks or remove material. Leave jewelry, polished pieces and specimens you want to preserve untested. If the grains are too small to examine separately, ask a geology educator or mineral identification service for help. Don’t crush, heat or use acids on an unknown find to settle this comparison.
Common questions
Is pyrite metallic?
Yes. The University of Minnesota lists pyrite’s luster as metallic and opaque. The U.S. Geological Survey says the metallic luster comes from its iron and the yellowish hue from its sulfur. That luster and color are why pyrite is so often mistaken for gold. Gold is metallic too, according to Cochise College, so compare hardness and streak instead.
Is every gold-colored mineral pyrite?
No. The U.S. Geological Survey also names chalcopyrite and biotite among minerals mistaken for gold. A metallic-looking flash could come from any of these, so look closely before you settle on a name.
Does a heavy rock mean it contains gold?
Heft alone won’t establish that. The specific gravities in the table describe the minerals themselves. Weighing a rock with several minerals gives a result for the whole piece; it doesn’t isolate a few metallic specks. A dense specimen needs other supporting observations before you assign a name. Weight is also one of the signs a heavy rock is a meteorite, and it isn’t proof there either.
Can pyrite contain real gold?
Yes. USGS notes that gold can occur within pyrite’s mineral structure. That doesn’t tell you whether your piece contains gold, or how much, and identifying a visible grain as pyrite can’t measure any gold it may contain.
Record what you can actually see
Use this checklist before asking someone to identify your find:
- Where was it found or bought, and what label came with it?
- Are the gold-colored areas loose grains, crystals, patches or tiny specks?
- What shapes or lines can you see on their surfaces?
- Do any existing test results identify the exact grain tested?
- Which observations are still unknown?
A fictional note might read: “White rock with several brassy, block-shaped grains. Fine lines visible on one face. No hardness or streak test. Possible pyrite; identification unconfirmed.”
Take a photo of the whole specimen and a close view of the metallic area. Our rock photography guide will help you capture the detail. In RockLens for iPhone, compare the suggested candidates and keep your photos and notes together. A photo suggestion can guide your next observation; it cannot confirm gold content.