1. Streak: The color of a mineral's powder when rubbed against a streak plate (unglazed porcelain). This is often a more reliable indicator of a mineral's identity than its external color, which can be affected by impurities or weathering.
2. Hardness: A mineral's resistance to scratching. This is measured on Mohs Hardness Scale, with 1 being the softest (talc) and 10 being the hardest (diamond). You can test hardness by seeing if a mineral can scratch another, or if a known hardness object can scratch it.
3. Cleavage: The tendency of a mineral to break along specific planes of weakness. This creates smooth, flat surfaces. Cleavage can be described as perfect, good, poor, or absent.
4. Fracture: How a mineral breaks when it does not cleave. This can be described as conchoidal (smooth, curved surfaces like glass), uneven (jagged), or fibrous (stringy).
5. Luster: The way a mineral reflects light. Luster can be metallic (shiny like a metal), glassy (like glass), pearly (like a pearl), dull (non-reflective), or earthy (like soil).
These properties, in combination with other characteristics like color, crystal shape, and density, can help you confidently identify many minerals.
