Streak plates are a specialty tool used by geologists to help identify rocks.
In the process of mineral identification, determining the streak color is a simple step that can help differentiate between various types.
To use, simply scratch a rock against one of the plates, or you can crush a piece of the rock and smear it on the plate. The different plate colors are used to help see the different streak colors better.
The color of a rock’s streak ofter differs from the color of the rock. A streak test of pyrite (fool’s gold) is blackish, while real gold produces a gold streak.
If a mineral does not leave a streak, this is also valuable information. Since the plate has a hardness of about 7 on the Mohs hardness scale, a mineral that leaves no streak has a hardness of >7.
You will receive a pair of streak plates, one black and one white.