Mineral Properties
Elementary School
Definition
The physical and chemical characteristics used to identify minerals, such as hardness, colour, lustre, streak, and crystal shape. Because each mineral has a consistent set of properties, geologists use them to tell minerals apart.
Worked examples
Quartz: hardness 7 on Mohs scale, glassy lustre, no cleavage, white streak, hexagonal crystals
This specific combination of properties uniquely identifies quartz among minerals.
Pyrite (fool's gold) vs. Gold: pyrite has hardness 6–6.5 and greenish-black streak; gold has hardness 2.5–3 and yellow streak
Testing hardness and streak reveals these are different minerals despite similar colour.
Common mistakes
- identifying a mineral by colour alone → testing multiple properties (hardness, streak, lustre, cleavage) together Many different minerals share the same colour, so colour alone is unreliable for identification.
- confusing streak with the mineral's surface colour → streak is the colour of the powder left when the mineral is rubbed on unglazed porcelain A mineral's streak colour often differs from its appearance; hematite looks metallic grey but has a red streak.
- thinking all shiny minerals have the same lustre → lustre types include metallic, glassy, pearly, silky, and dull The quality of how light reflects varies; pyrite is metallic, quartz is glassy, and talc is pearly.
Where you'll use it next
You'll use mineral properties when studying rock classification, the rock cycle, and Earth's structure, and later in identifying ore minerals in economic geology and understanding material science.
See also
Reviewed by Pat Cheng, M.Ed. — StudyPug Curriculum Lead · Last updated June 6, 2026