Mineral Identification (Part 3)
Color and Streak
Color and streak are related properties that have to do with color in minerals.
Color refers to the overall color of the mineral sample. Color is easy to see, but is not a reliable way to identify a mineral. Some minerals show many different colors.
Quartz is an example of a mineral that occurs in many different colors. Rose quartz, smoky quartz (black or gray), amethyst (purple), and clear quartz are some of the examples of color variation in quartz. (Photographs by Parvinder Sethi)
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Streak is the color of a powdered sample of the mineral. The streak test is done by rubbing the mineral on a streak plate, which is a small piece of unglazed porcelain. The streak of a mineral is a more reliable way to identify a mineral.
A mineral’s streak is a good identification tool. Hematite, shown left, has a reddish brown streak. The mineral galena, shown right, makes a black streak on the streak plate. (Photographs by Parvinder Sethi)
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