Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Star Rose Quartz
Rose quartz that displays a six-rayed star (asterism) when cut as a cabochon, caused by microscopic rutile-like inclusions.
gemstone
Golden Healer Quartz
Quartz colored or coated by golden iron oxides such as limonite or goethite, giving a warm sunlit yellow glow.
crystalLemurian Seed Quartz
Clear quartz crystals marked by distinctive horizontal ladder-like striations, popularized from Brazil as a metaphysical stone.
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
Lepidolite
A soft lithium-bearing mica with a lilac to purple color and pearly, flaky sheen, an important ore of lithium.
mineral
Greenschist
A green, foliated low-grade metamorphic rock colored by chlorite, actinolite, and epidote, marking the greenschist metamorphic facies.
metamorphic
Blueschist
A blue-hued, high-pressure metamorphic schist colored by the amphibole glaucophane, formed in cold, deep subduction zones.
metamorphic
Phyllite
A fine-grained foliated metamorphic rock between slate and schist, recognized by its silky silvery sheen and wavy, crinkled surfaces.
metamorphicNordmarkite
A light-colored alkali quartz syenite dominated by perthitic feldspar with minor quartz, from the Oslo igneous province of Norway.
igneousWhiteschist
A rare high-pressure metamorphic schist defined by the diagnostic assemblage of talc plus kyanite, often pale and silvery.
metamorphic
Kersantite
A dark mica lamprophyre with biotite and augite phenocrysts in a plagioclase-dominated groundmass, the feldspar counterpart of minette.
igneous
Green Aventurine
A green quartz speckled with shimmering fuchsite mica that produces a glittering aventurescence, popular as an affordable ornamental stone.
mineral
Itabirite
A metamorphosed banded iron formation of alternating quartz and iron-oxide layers, mined as a major iron ore.
metamorphic
Amphibolite
A dark, dense metamorphic rock dominated by hornblende and plagioclase, formed by medium- to high-grade metamorphism of basalt.
metamorphic
Metarhyolite
Rhyolite that has been metamorphosed, recrystallizing its silica-rich volcanic material into a tougher felsic metamorphic rock.
metamorphic
Minette
A dark, mica-rich lamprophyre dike rock in which biotite and augite phenocrysts sit in a groundmass dominated by alkali feldspar.
igneous
Glauconite
A soft, green iron-potassium mica that forms in marine sediments and gives greensand its characteristic olive color.
mineralPrase
An old name for a dull leek-green variety of quartz or chalcedony colored by green mineral inclusions, historically called mother of emerald.
crystal
Soapstone
A soft, talc-rich metamorphic rock with a soapy feel, easily carved and highly heat-resistant for cookware and sculpture.
metamorphicGondite
A metamorphic rock made chiefly of manganese-rich spessartine garnet and quartz, formed from ancient manganese-bearing sediments.
metamorphic
Chalcedony
A waxy, translucent microcrystalline form of quartz that serves as the parent group for agate, jasper, carnelian, and onyx.
mineral
Ametrine
A natural bicolor quartz that combines purple amethyst and golden citrine in a single crystal.
crystal
Citrine
The golden-yellow variety of quartz, ranging from pale lemon to deep madeira amber, often produced by heating amethyst.
gemstone
Herkimer Diamond
Exceptionally clear, naturally double-terminated quartz crystals from Herkimer County, New York, prized for their diamond-like brilliance.
crystal