STREAK: The streak (also called "powder color") of a mineral is the color of the powder produced when it is dragged across an un-weathered surface.
CLEAVAGE: Cleavage refers to how some minerals break along flat planes when exposed to stress, such as being hit with a hammer.
How is streak important to identifying a mineral?-
The color of a mineral's powder is often a very important property for identifying the mineral. The streak test is done by scraping a specimen of the mineral across a piece of unglazed porcelain known as a "streak plate." This can produce a small amount of powdered mineral on the surface of the plate.
How is cleavage important to identifying a mineral?-
Cleavages are described in terms of their quality - how smoothly the mineral breaks - and their difficulty - how easy, or how hard, it is to produce the cleavage. The quality of cleavages are perfect, imperfect, distinct, good, fair, and poor. The difficulty is described as easy, hard, and difficult to produce. So, cleavage can be used to identify minerals on the Mohs’ hardness scale.
