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Stone Science

Common rock-forming minerals

Scientific names and quick identifiers for the minerals that make up most rocks.

Quartz geode crystals representing common silicate minerals
Major groups

The essentials

Quartz

SiO₂; no cleavage; conchoidal fracture; common in granites and sandstones.

Feldspars

Plagioclase + K-feldspar; two cleavages; dominate many igneous rocks.

Micas

Biotite/muscovite; perfect basal cleavage; platy habit.

Amphiboles & pyroxenes

Dark silicates; cleavage angles differ; common in mafic rocks.

Olivine

Green Mg-Fe silicate; granular; common in basalt and ultramafics.

Carbonates

Calcite/dolomite; acid reaction (calcite); common in limestones and marbles.

Mineral close-ups

Representative mineral textures for reference (field ID should use multiple properties).

Agate banding (microcrystalline quartz) Calcite mineral set Pyrite texture (sulfide example) Garnet crystals
Agate banding (microcrystalline quartz) Calcite mineral set Pyrite texture (sulfide example) Garnet crystals
Agate banding (microcrystalline quartz) Calcite mineral set Pyrite texture (sulfide example) Garnet crystals
Agate banding (microcrystalline quartz) Calcite mineral set Pyrite texture (sulfide example) Garnet crystals
Agate banding (microcrystalline quartz) Calcite mineral set Pyrite texture (sulfide example) Garnet crystals
Agate banding (microcrystalline quartz) Calcite mineral set Pyrite texture (sulfide example) Garnet crystals

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