Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Aventurine
A translucent quartz speckled with glittery mineral inclusions that produce a shimmering aventurescence, most often green.
crystal
Flower Jasper
A jasper whose radiating mineral clusters form flower-like rosettes scattered across an earthy background.
mineral
Green Aventurine
A green quartz speckled with shimmering fuchsite mica that produces a glittering aventurescence, popular as an affordable ornamental stone.
mineral
Spherulitic Obsidian
Obsidian containing spherulites — small radiating spheres of feldspar and cristobalite that crystallized within the cooling volcanic glass.
igneous
Mintabie Opal
Precious opal from the Mintabie field in South Australia, known for hard, bright crystal opal and some dark-bodied stones.
gemstone
Grape Agate
Clusters of tiny botryoidal chalcedony spheres resembling bunches of grapes, famously purple, found in Indonesia.
mineral
Prasiolite
A pale green variety of quartz, usually created by heat-treating amethyst, often marketed as green amethyst.
gemstone
Gondite
A metamorphic rock made chiefly of manganese-rich spessartine garnet and quartz, formed from ancient manganese-bearing sediments.
metamorphic
Brazilian Opal
Precious opal from Brazil, especially the Pedro II area of Piaui, known for bright, often stable crystal and white opal.
gemstone
Halite
The natural mineral form of table salt, a soft, water-soluble evaporite that forms perfect cubic crystals and tastes salty.
mineral
Chevron Amethyst
A naturally banded quartz combining purple amethyst and white quartz in striking V-shaped chevron or zigzag patterns.
crystal
Mariposite
A green, gold-associated metamorphic rock made of chrome-rich mica and quartz, named for Mariposa County in California's gold country.
metamorphic
Andamooka Opal
Precious opal from the Andamooka field of South Australia, famous for solid crystal opal and its distinctive treatable matrix opal.
gemstone
Quartzite
An extremely hard metamorphic rock formed from sandstone, made of fused quartz grains that break across rather than between the grains.
metamorphic
Latite
The fine-grained volcanic equivalent of monzonite, an intermediate lava with nearly equal feldspars and little free quartz.
igneous
Carnelian
A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.
gemstone
Tonalite
A quartz-rich plutonic rock dominated by plagioclase feldspar with little alkali feldspar, closely related to granodiorite and quartz diorite.
igneous
Super Seven
A trade name for quartz containing a combination of seven minerals including amethyst, smoky quartz, and cacoxenite, prized by collectors.
crystal
Monzonite
An intermediate plutonic rock with nearly equal alkali and plagioclase feldspar and very little quartz, sitting between diorite and syenite.
igneous
Sandstone
A clastic sedimentary rock made of cemented sand grains, often quartz, recording ancient beaches, deserts, and rivers.
sedimentary
Quartzite Sandstone
A tough, quartz-rich sandstone cemented by silica, transitional toward true quartzite but still sedimentary in origin.
sedimentary
Kyanite Schist
A mica schist containing bladed blue kyanite crystals, a marker of medium- to high-grade metamorphism of aluminous rocks.
metamorphic
Metaquartzite
A hard, tough metamorphic rock of fused quartz grains, formed by recrystallizing quartz sandstone under heat and pressure.
metamorphic
Dumortierite
A hard aluminum borosilicate famous for its rich denim-blue color, often forming dense fibrous masses or coloring quartz blue.
mineral