Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Pyrite
The brassy iron sulfide mineral famous as 'fool's gold,' known for sharp metallic cubes and a much higher hardness than real gold.
mineral
Arsenopyrite
A silver-white iron arsenic sulfide and the most common arsenic mineral, known for striking sparks and a garlic smell when struck.
mineral
Grape Agate
Clusters of tiny botryoidal chalcedony spheres resembling bunches of grapes, famously purple, found in Indonesia.
mineral
Pyrrhotite
A bronze-colored iron sulfide notable for being the most magnetic of the common sulfide minerals and an important nickel host.
mineral
Chalcopyrite
A brassy copper-iron sulfide that is the world's most important copper ore, often showing colorful iridescent tarnish.
mineral
Psilomelane
A field term for hard black massive manganese oxides, often botryoidal, mined as an important manganese ore.
mineral
Peacock Ore
A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.
mineral
Fire Agate
A rare brown chalcedony containing thin iron-oxide layers that produce flashing, fiery rainbow iridescence like trapped flames.
gemstone
Chrome Pyrope
A chromium-rich pyrope garnet whose intense blood-red color comes from chromium, often mined from ant hills and kimberlite weathering.
gemstone
Pyrope Garnet
The magnesium-rich garnet famed for its intense blood-red 'fire,' historically the Bohemian garnet of Victorian jewelry.
gemstone
Lapis Lazuli
An intensely blue metamorphic rock of lazurite flecked with golden pyrite, prized for millennia as a gemstone and ultramarine pigment.
metamorphic
Black Shale
Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.
sedimentary
Bumblebee Jasper
A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.
sedimentary
Sodalite
A royal-blue feldspathoid mineral with white calcite veining, often confused with lapis lazuli but lacking its golden pyrite flecks.
mineral
Hyalite Opal
A clear, glassy, botryoidal common opal famous for its intense green fluorescence under UV light, caused by trace uranium.
gemstone
Smithsonite
Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.
mineral
Goethite
Goethite is a common brown iron oxyhydroxide, the main crystalline component of limonite and rust, with shimmering botryoidal forms.
mineral
Hemimorphite
A hydrous zinc silicate, often sky-blue, that is an ore of zinc and a collectible mineral forming botryoidal crusts and crystals.
mineral
Prehnite
A translucent yellow-green silicate famous for its botryoidal 'grape' clusters, often hosting needle-like sprays of black epidote.
mineral
Millerite
A nickel sulfide famous for delicate brass-yellow hairlike crystals that form radiating sprays inside cavities and geodes.
mineral
Bohemian Garnet
Small, intensely red chrome-pyrope garnets from the Czech Bohemian region, famous for densely set antique Victorian jewelry.
gemstone
Arizona Ruby
Arizona Ruby is a chromium-rich pyrope garnet from Arizona, often gathered from anthills, valued for its intense ruby-like red.
gemstone
Ant Hill Garnet
Small, bright chrome-pyrope garnets famously brought to the surface by harvester ants on the Navajo lands of Arizona.
gemstone
Cape Ruby
Cape Ruby is a deep red pyrope garnet from South African diamond deposits, prized as an affordable, fiery alternative to ruby.
gemstone