The color of the powder produced by a mineral is called

• A. Luster
• B. Color
• C. Streak
• D. Hardness

Answer: (C)

Streak is the color of a mineral’s powder when you rub the mineral on a hard, unglazed porcelain plate. This test reveals the powder color rather than the surface color, which can vary due to impurities, weathering, or coatings. Because the surface appearance can be misleading, streak often provides a more consistent clue about a mineral’s identity. For example, hematite can look metallic and gray, but its powder leaves a reddish-brown streak. Keep in mind that if the mineral is harder than the plate, it may not leave a powder at all. Luster describes how light reflects from a surface, hardness is how easily a mineral is scratched, and color is the mineral’s overall surface hue; streak specifically refers to the powder color left behind.