Minerals
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Minerals |
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Streak |
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The streak is the color of the powdered form of the mineral. You determine the streak by scratching a mineral against a porcelin plate (called a streak plate--the white square in photo below) and then describing the color of the powdered mineral. The streak of a mineral is very diagnostic of some minerals, particularly because the mineral's color and streak may be different, as the photo below shows. In this example, the mineral is dark brown to black, but the streak is red-brown in color... |
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However, in other cases the streak is not diagnostic, and for some very hard minerals, you can not determine a streak, because the mineral may be harder than the streak plate (hardness=7). |
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