The Importance of Physical and Chemical Properties in Mineral Identification

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?). 

The Importance of Physical and Chemical Properties in Mineral Identification
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||




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.


Observable Characteristics and Tests for Identifying Minerals
Easily Observable Characteristics
Simple Tests Requiring Equipment
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


See also: How do Geologists identify minerals?

How to Identify Minerals in 10 Steps (photos)
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