Streak

What Would You Like to Know?

-What is streak?
The streak of a mineral is the color of the powder left on a streak plate (piece of unglazed porcelain) when the mineral is scraped across it. The streak plate has a hardness of glass, so minerals with a Mohs Hardness >7 will scratch the streak plate and won’t powder the mineral.

-Where do you observe streak?
A minerals streak is determined by rubbing it on a streak plate, which is a piece of unglazed porcelian. The streak plate is essentially a type of glass so it isn’t used on minerals with a hardness greater than 7.

-How useful is streak in identifying minerals?
Streak can be useful for identifying metallic and earthy minerals. Nonmetallic minerals usually give a white streak because they are very light-colored. Other minerals may have very distinctive streaks; hematite, for example, always gives a reddish brown streak no matter what type of luster it displays.