01
Composition
Which elements and ions are present, in what proportions, and with what substitutions?
Composition · crystal structure · properties · identification
Mineralogy
Mineralogy connects chemistry to crystal structure and crystal structure to observable properties. Minerals are defined by composition and ordered structure, then identified by converging evidence from tests such as hardness, streak, cleavage, luster, density, crystal habit, and special reactions.
Structure → property chain
A mineral's appearance is the surface expression of atomic structure.
That is why cleavage planes, crystal symmetry, hardness, density, optical effects, and fracture patterns are not arbitrary labels. They emerge from bonding and the repeated arrangement of matter.
02
Crystal structure
How are those atoms or ions arranged and repeated through the solid?
03
Mineral properties
Structure and bonding produce hardness, cleavage, fracture, density, luster, optical behavior, and other observable traits.
04
Identification
Compare multiple diagnostic properties against known minerals rather than trusting appearance alone.
Diagnostic bench
Identify minerals by converging evidence.
Color alone is unreliable. A field identification gets stronger when hardness, streak, cleavage or fracture, luster, crystal habit, density, and special reactions point toward the same mineral.
Silicate
Quartz
SiO₂
LusterVitreous
Hardness7
StreakWhite
CleavageNone · conchoidal fracture
Choose a diagnostic test
Observed result
7 on the Mohs scale
No single result identifies every specimen. Use several independent properties and eliminate alternatives.
Classification · reference, not navigation
Chemical families organize minerals by their dominant anion or anionic group.
The full mineral-classification system is more detailed than this overview, but family-level grouping makes common chemical relationships visible before diving into individual species.
01
Silicates
Built around silicon-oxygen structural units; the dominant mineral family in Earth's crust.
02
Carbonates
Contain carbonate groups and often record sedimentary, marine, hydrothermal, or metamorphic environments.
03
Oxides
Oxygen bonded to one or more metallic elements; important as ores and weathering products.
04
Sulfides
Sulfur combined with metals or metalloids; many economically important ore minerals belong here.
05
Halides
Salts containing halogen ions such as chloride or fluoride; often associated with evaporite settings.
06
Native elements
Minerals dominated by a single element, including gold, copper, sulfur, graphite, and diamond.