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Mineral Streak Test Colour Chart

A mineral streak is the apparent colour of a mineral in powdered form, commonly observed as residue on unglazed porcelain. Streak may differ from the colour of the specimen surface, but it is one clue rather than a complete identification. Common contrasts include a red to red-brown streak for hematite, black for magnetite, dark greenish-black to brownish-black for pyrite, golden yellow for native gold, lead-grey for galena, and black to dark grey for graphite. Many silicates and pale nonmetallic minerals have white streaks, so white commonly produces a broad candidate group. Quartz and other minerals near or above the hardness of a common streak plate may gouge the porcelain or create white plate powder instead of a trustworthy mineral streak. Wipe loose powder away and distinguish deposited mineral powder from a persistent groove. Do not abrade an unknown, valuable, fragile, fibrous, radioactive, contaminated, or potentially arsenic-, mercury-, lead-, or silica-bearing specimen. Prefer published reference data and combine any existing streak observation with hardness, lustre, cleavage, habit, magnetism, density, and geologic context. GeoMiner's lookup accepts no specimen name or free text, counts only a bounded colour category and tool action, and hands the observation to Quick ID without an account.

Verification resources

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

  • Minerals — physical properties — U.S. National Park Service. Definition of streak as the residue left on unglazed porcelain and the need to combine physical properties.
  • What is Fool's Gold? — U.S. Geological Survey. Published streak contrasts among native gold, pyrite, chalcopyrite, and common micas.
  • I think I found a meteorite. How can I tell for sure? — U.S. Geological Survey. Limits of streak screening and the red/black contrast for hematite and magnetite.
  • Iron — Minerals Education Coalition. Reference streak, hardness, colour, and magnetism data for hematite and magnetite.
  • Pyrite — Minerals Education Coalition. Reference streak, hardness, colour, lustre, and fracture data for pyrite.
  • Graphite — Minerals Education Coalition. Reference streak, hardness, colour, lustre, and flaky habit data for graphite.
  • Quartz — Minerals Education Coalition. Reference white streak, Mohs hardness 7, and variable surface colour for quartz.
  • Fluorite — Minerals Education Coalition. Reference white streak, Mohs hardness 4, variable colour, and cubic/octahedral habit for fluorite.
  • Mercury — Minerals Education Coalition. Reference scarlet streak and Mohs hardness data for cinnabar, plus the toxicity context for mercury.
  • Copper — The Ancient Metal — Minerals Education Coalition. Reference hardness, habit, and streak clues for native copper, malachite, azurite, and chalcopyrite.
  • Lead — Minerals Education Coalition. Galena as the principal lead ore and the toxicity context for lead-bearing material.
  • Silica and Worker Health — CDC / NIOSH. Why cutting, grinding, polishing, and drilling silica-bearing rock can create hazardous respirable dust.

Read GeoMiner's editorial methodology.

Common questions

What is a mineral streak?
Streak is the apparent colour of a mineral in powdered form, commonly observed as residue on unglazed porcelain. It can differ from the colour of the specimen surface.
Why did my mineral leave no streak?
A mineral harder than the plate may scratch or gouge the porcelain instead of leaving useful powder. A weathered coating, too little pressure, or an unsuitable glazed surface can also obscure the result.
Is streak enough to identify a mineral?
No. Many minerals share white or dark streaks. Combine an existing streak observation with hardness, lustre, cleavage, habit, magnetism, density, and geologic context.
Can I streak-test any unknown rock or mineral?
No. Do not abrade an unknown, valuable, fragile, fibrous, radioactive, contaminated, or potentially arsenic-, mercury-, lead-, or silica-bearing specimen. Use published data or qualified laboratory procedures when safety or consequence matters.
What is the difference between a streak and a scratch?
A streak is loose mineral powder deposited on the plate. A scratch is a persistent groove in the porcelain, sometimes accompanied by white plate powder. Wipe loose material away and inspect the surface before interpreting the mark.

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