1. Color: While not always reliable, color can be a starting point. Some minerals have distinctive colors (e.g., gold, pyrite). However, impurities can drastically change a mineral's color.
2. Streak: The color of a mineral's powder when rubbed against a streak plate (unglazed porcelain). This is often more consistent than the mineral's overall color.
3. Luster: How light reflects off a mineral's surface. Descriptions include metallic, glassy, pearly, dull, etc.
4. Hardness: A mineral's resistance to scratching. Measured on Mohs Hardness Scale (1-10). For example, a fingernail has a hardness of 2.5.
5. Cleavage/Fracture: How a mineral breaks. Cleavage results in smooth, flat surfaces, while fracture is an irregular break.
6. Crystal Habit: The shape a mineral typically forms. This can be cubic, hexagonal, or other geometric shapes.
Note: These characteristics are often used in combination to identify minerals. For example, a mineral with a metallic luster and a yellow streak is likely pyrite (fool's gold).
