Black porcelain streak plates are great for testing minerals. Often, the color of the

mineral's streak is a clue as to the identification of the mineral. To perform
the test, rub the mineral on the plate and observe the color. The streak is the
color of the mineral in powder form. Many minerals have a streak that is the
same as its outward appearance; however, some streaks are very different
colors! Black streak plates are great for light colored samples. Each streak
plate is 2” x 2”.