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Mineral definition
To be classified as a "true" mineral, a substance must be a solid, arising from geological processes, and having a crystal structure. Traditionally, it must also be an inorganic, naturally occurring, homogeneous substance with a defined chemical composition, but now organically derived substances that have been transformed into a crystalline structure are minerals.
Common Nonminerals
- Allingite, another name for amber.
- Amber, organic, non-crystal structure.
- Anthracite, a variety of coal, "hard coal."
- Beckerite, another name for amber.
- Burmite, another name for amber.
- Coal, organic, non-homogeneous, and non-crystal structure.
- Coprolite, fossilized feces, a fossil of organic origin.
- Coquina, non-homogeneous, non-crystal limestone formed from marine shells and coral.
- Gedanite, another name for amber.
- Gilsonite, natural asphalt.
- Glessite, another name for amber.
- Jet, not considered a true mineral due to organic, non-crystal nature, a mineraloid.
- Krantzite, another name for amber.
- Lignite, a variety of coal, "brown coal."
- Limonite, amorphous hydrated iron oxide, a mineraloid.
- Obsidian, usually not considered a mineral due to non-crystal structure.
- Opal, non-crystal structure, a mineraloid.
- Pearl, often considered a mineral due to crystal components, but then not a mineral due to organic origin, probably should be a mineraloid.
- Petroleum, organic and liquid.
- Rocks, most rocks are mixtures of minerals, but some are composed of just one mineral.
- Pyrobitumen, organic, nonhomogeous, non-crystal structure.
- Stantienite, another name for amber.
- Synthetic diamond, not naturally occurring like most other synthetic gems, but difficult to distinguish from naturally occurring forms.
- Vulcanite, vulcanized natural or synthetic rubber, thus not a mineral due to organic composition, lack of crystal structure, and not naturally occurring.
- Water, a liquid (but naturally occurring ice is a mineral).
Other considerations
Some minerals, such as the well-known Apatite and Mica, are not homogeneous substances, but are a mixture of related minerals, sometimes referred to as a mineral group.
See also
