A mineral is a naturally occurring, inorganic solid with a definite chemical composition and an ordered crystalline structure.
Key Criteria
This definition, widely accepted by organizations like the International Mineralogical Association, requires five essential traits: natural formation through geological processes, inorganic origin (not from living organisms), solid state, specific chemical makeup (often a single element or compound), and a highly organized atomic arrangement forming crystals.
Common Examples
Quartz, feldspar, calcite, and halite (rock salt) meet these criteria, while substances like coal (organic) or synthetic diamonds do not.
Broader Context
Rocks differ as aggregates of one or more minerals, and homogeneity ensures predictable properties like hardness and density.
