Mineral Hardness Identification Guide
Identify minerals by Mohs hardness (1-10), streak color, and luster.
Includes household scratch tests for each hardness level and a table of 30 minerals.
Mohs Hardness Scale Developed by Friedrich Mohs in 1812, this scale ranks minerals from 1 (softest) to 10 (hardest) based on scratch resistance. A mineral can scratch anything softer than itself.
Common Reference Objects Fingernail ≈ 2.5, Copper coin ≈ 3.0, Iron nail ≈ 4.0, Glass plate ≈ 5.5, Steel file ≈ 6.5.
Streak Test The streak is the colour of a mineral’s powder, often different from the mineral surface colour. It is tested by scratching the mineral across an unglazed porcelain tile.
Luster Luster describes how light reflects from the mineral surface — metallic, glassy (vitreous), pearly, silky, or dull.