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Other Uses for Streak Plates
In addition to their use in doing the streak test, streak plates can be used any time you need a small amount of powdered mineral. In doing the acid test to distinguish calcite from dolomite, dolomite might require being powdered to show effervescence with dilute hydrochloric acid. Simply use the streak plate to make some powder of your specimen and add acid…
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Refreshing Your Streak Plate
Streak plates that have been used heavily will be covered with streaks and powdered mineral. They can easily be cleaned with water and a piece of wet or dry 220 grit sandpaper. Aluminum oxide or silicon carbide sandpaper works best because the granules are hard enough to smooth the surface of the streak plate. The…
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Don’t Be Deceived!
A number of things can cause a streak test to give unreliable results. To avoid problems, keep the following items in mind.
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Why Use the Streak Test?
The streak test is valuable because many minerals occur in a variety of apparent colors – but all specimens of that mineral share a similar streak color. For example: specimens of hematite can be black, red, brown, or silver in color and occur in a wide variety of habits; however, all specimens of hematite produce a streak with…
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Don’t Be Wimpy!
The most common error made by people who are doing the streak test for the first time is to lightly rub the specimen back and forth on the surface of the streak plate. This will not produce a proper streak. Some mineral specimens are so hard that very firm pressure and determination are required to…
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How to Conduct the Streak Test
The streak test should be done on clean, unweathered, or freshly broken specimens of the mineral. This is done to reduce the possibility that a contaminant, weathered coating, or tarnish will influence the results of the test. The preferred method for conducting a streak test is to pick up a representative specimen of the mineral…
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What is the Streak Test?
The “streak test” is a method used to determine the color of a mineral in powdered form. The color of a mineral’s powder is often a very important property for identifying the mineral. The streak test is done by scraping a specimen of the mineral across a piece of unglazed porcelain known as a “streak plate.” This…