How can physical and chemical properties of minerals be used for their identification?
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Photos from the left to right.
Tourmaline Majesty credit: Orbital Joe.|| Zoisite var. Tanzanite photo: mim museum.|| Elbaite with albite and Lepidolite.|| Rubellite Tourmaline, Quartz, MIca, Cleavelandite and Orthoclase.? DI (FH) Rudolf Watzl || Fluorite on sphalerite (Elmwood, TN, USA) || A slice of an amethyst by Rob Lavinsky||
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All minerals have unique properties that aide in their identification. Some minerals have “unique” characteristics that have an appearance or characteristic that make them easy to identify. However, these identifying characteristics may not be easy to determine without extensive testing more extensive testing.
Fortunately, the most common minerals are fairly easy to identify by general appearance or with simple tests for hardness, crystal form, color, magnetism, and “streak” (does it leave a colored line when scratched on a piece of tile?).
Note that some tests can be destructive to mineral samples (such as measuring hardness, streak, malleability, elasticity, and testing with acid). In addition, tasting a mineral is not recommend – some are actually poisonous! Washing your hands after handling mineral samples is always recommended.
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Observable Characteristics and Tests for Identifying Minerals
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Easily Observable Characteristics
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Simple Tests Requiring Equipment
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crystal form
color cleavage luster (metallic, non-metallic) diaphaneity (transparent, translucent or opaque) double refraction striations feel odor (smell) taste |
hardness
magnetism streak acidic reaction specific gravity malleability elasticity electrical resistivity fluorescence phosphorescence radioactivity thermoluminescence |