24/08/2026
🪨 MINERAL IDENTIFICATION: 5 SIMPLE TESTS EVERY GEOLOGY & MINING STUDENT SHOULD KNOW
Mineral identification is one of the fundamental practical skills in geology, mining engineering, geotechnical engineering. While advanced laboratory techniques provide detailed mineralogical information, simple physical tests can help identify an unknown mineral in the field.
🔹 1. HARDNESS – MOHS SCALE
Hardness measures a mineral’s resistance to scratching. Common reference objects include:
✋ Fingernail ≈ 2.5
🪙 Copper penny ≈ 3.5
🪟 Glass ≈ 5.5
🔩 Steel nail ≈ 6.5
Quartz has a Mohs hardness of 7 and can scratch glass.
🔹 2. STREAK – THE POWDERED COLOUR
Streak is the colour of a mineral in powdered form. It is determined by rubbing the mineral across an unglazed porcelain streak plate.
Examples:
• Hematite → reddish-brown/red streak
• Galena → gray streak
• Kaolinite → white streak
• Goethite → brown streak
🔹 3. LUSTER – HOW THE MINERAL REFLECTS LIGHT
Luster describes how light is reflected from a mineral surface.
⚙️ Metallic – Galena, Pyrite and Chalcopyrite
💎 Glassy (vitreous) – Quartz
✨ Pearly – Muscovite
🪨 Earthy/Dull – Kaolinite
🔹 4. CLEAVAGE – HOW THE MINERAL BREAKS
Cleavage refers to the tendency of a mineral to break along planes of weakness related to its crystal structure.
• Cubic/blocky – Galena
• Sheet-like – Muscovite (mica)
• Irregular/uneven fracture – Quartz
🔹 5. COLOUR – USEFUL, BUT WITH CAUTION
Colour is one of the easiest properties to observe, but it should not be used alone. The same mineral can occur in different colours due to impurities, chemical substitutions and alteration. Likewise, different minerals may have similar colours.
🎯 THE KEY LESSON
Reliable mineral identification comes from combining several properties rather than depending on a single observation:
Hardness + Streak + Luster + Cleavage + Colour = Better identification.
Mineral composition influences rock and soil behaviour. In mining, identification supports geological mapping, ore identification, material characterization and assessment of weathering or alteration.
These field observations also provide a foundation for advanced methods such as XRD, XRF, petrographic microscopy and SEM-EDS.
👉 Don’t just look at a mineral—test it and identify it systematically.
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