* Hardness: Shale is relatively soft, with a Mohs hardness of 2-3. This means you can scratch it with a fingernail (hardness 2.5) but not with a copper coin (hardness 3-3.5).

* Luster: Shale typically has a dull or earthy luster. It might appear slightly waxy or greasy, but not shiny like a metal.

* Streak Color: The streak color of shale is usually grayish-white or light brown. You determine the streak by rubbing the shale against a streak plate (unglazed porcelain) to see the color of the powdered mineral.