Mineral identification

Mineral identification is the determination of a mineral’s identity from its physical and chemical properties. It combines observable tests with measurements and, when needed, laboratory analysis.

Mohs scale of mineral hardness: A scale ranking minerals by their resistance to scratching, from talc at 1 to diamond at 10. Scratch resistance offers a simple comparative test, though hardness alone rarely identifies a specimen.
Mineral streak: The color of a mineral in powdered form, usually observed on an unglazed porcelain plate. It is the result interpreted in a streak test and can differ from surface color.
Field geology: The study of geological materials and structures through observations and measurements made outdoors. Geologists use rapid mineral tests to interpret rocks directly at outcrops.
Mineral: A naturally occurring, generally inorganic solid with an ordered atomic structure and characteristic chemical composition. Identification depends on deciding whether a material meets the definition of a mineral.
Streak test: A test that identifies a mineral’s powdered color by rubbing it across an unglazed porcelain plate. Powder color can remain consistent when a mineral’s surface color varies.
Optical mineralogy: The study and identification of minerals using their interactions with light, especially in thin section. Polarized-light observations resolve grains too small or similar for hand tests.
Petrography: The description and classification of rocks, including their mineral content and texture. Identifying constituent minerals is a foundation of naming and interpreting rocks.
Rock: A naturally occurring solid aggregate of one or more minerals or mineraloids. A rock is identified by its assemblage, while mineral identification concerns an individual substance.
Cleavage (crystal): The tendency of a mineral to break along planes of weak atomic bonding. Cleavage directions and angles help distinguish minerals with similar appearances.
Polarizing microscope: A microscope fitted with polarizers and other optical components for examining anisotropic materials. It reveals optical properties that help identify minerals in thin sections.

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