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Mineral Lustre (Luster) Chart

Mineral lustre—spelled luster in American English—is the quality and intensity of light reflected from a surface. It is not the specimen colour or transparency. Begin with a clean, dry, existing surface in diffuse white light and rotate the specimen so the reflection moves. Metallic and submetallic surfaces resemble opaque metal. Common nonmetallic categories include vitreous or glassy, pearly, silky, resinous, waxy or greasy, and dull or earthy. Quartz, calcite, feldspar, fluorite, and olivine commonly appear vitreous. Mica, talc, and some gypsum surfaces may appear pearly. Parallel fibrous aggregates can appear silky. Sphalerite, sulfur, and some garnets may look resinous. Chalcedony, serpentine, and turquoise can look waxy or greasy, while clay minerals, earthy goethite, and earthy hematite show little directed reflection. One mineral can show different lustres on crystal faces, cleavage surfaces, fractures, weathered coatings, or fine-grained aggregates. Do not polish, wet, oil, grind, scratch, chip, or break an unknown to improve the view. GeoMiner's private lookup accepts only one bounded lustre category, records no specimen name, free text, photo, colour, or measurement, and hands the observation to Quick ID without an account. Confirm lustre with hardness, streak, cleavage, habit, density, and geologic context.

Verification resources

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

  • undefined. Lustre as the quality and intensity of reflected light, with metallic, glassy, dull, and earthy examples.
  • undefined. The metallic/nonmetallic split and vitreous, resinous, pearly, greasy or waxy, silky, and adamantine terminology.
  • undefined. Vitreous, waxy, and dull lustre variation plus conchoidal fracture and hardness for quartz.
  • undefined. Vitreous lustre, variable colour, hardness, crystal system, and fracture for fluorite.
  • undefined. Vitreous to pearly lustre and sheet-silicate context for biotite mica.
  • undefined. Pearly lustre, softness, sheet form, cleavage, and fracture for talc.
  • undefined. Vitreous to resinous lustre and group-level context for garnet.
  • undefined. Metallic lustre for molybdenite and vitreous lustre for wulfenite.
  • undefined. Greasy lustre as an observed clue for dark pyroxene in basalt and the limits of unaided field identification.
  • undefined. Why grinding, polishing, cutting, or breaking silica-bearing material can create hazardous respirable dust.

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Common questions

What is mineral lustre?
Lustre—spelled luster in American English—is the quality and intensity of light reflected from a mineral surface. It describes appearance rather than colour or transparency.
What is the difference between metallic and nonmetallic lustre?
Metallic minerals reflect light like an opaque metal surface. Nonmetallic lustres include vitreous or glassy, pearly, silky, resinous, waxy, greasy, dull, and earthy appearances.
How should I observe mineral lustre?
Use a clean, dry, existing surface in diffuse white light. Rotate the specimen and compare the reflection with familiar materials such as metal, glass, pearl, silk, resin, wax, or dry soil.
Can lustre identify a mineral by itself?
No. Weathering, coatings, grain size, surface roughness, and lighting can alter appearance, and many minerals share a lustre. Combine it with independent properties and geologic context.
Should I polish or break a specimen to see its lustre?
Not casually. Prefer a surface that already exists. Do not polish, grind, chip, wet, or abrade an unknown, valuable, fragile, fibrous, radioactive, contaminated, or potentially hazardous specimen.

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