1) Color: This is often one of the most noticeable characteristics, but can be deceiving as some minerals can have multiple colors.
2) Hardness: This is a measure of how resistant a mineral is to scratching or abrasion. The Mohs scale is used to compare the hardness of minerals.
3) Cleavage: This refers to the tendency of a mineral to break along certain planes, based on its internal crystal structure.
4) Fracture: This refers to how a mineral actually breaks, rather than how it's supposed to break along cleavage planes.
5) Luster: This describes how a mineral's surface reflects light, and can be classified as metallic, nonmetallic, or dull.
6) Streak: This refers to the color of the powder that a mineral leaves when rubbed on a streak plate, which can differ from the mineral's overall color.