Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Andamooka Opal
Precious opal from the Andamooka field of South Australia, famous for solid crystal opal and its distinctive treatable matrix opal.
gemstone
Andradite Garnet
The calcium-iron garnet species, ranging from brilliant green demantoid to golden topazolite and jet-black melanite.
gemstone
Pyrrhotite
A bronze-colored iron sulfide notable for being the most magnetic of the common sulfide minerals and an important nickel host.
mineral
Millerite
A nickel sulfide famous for delicate brass-yellow hairlike crystals that form radiating sprays inside cavities and geodes.
mineral
Andesine-Labradorite
An intermediate plagioclase feldspar spanning andesine and labradorite, marketed as a red-to-green gem, much of which is copper-diffusion treated.
gemstone
Arsenopyrite
A silver-white iron arsenic sulfide and the most common arsenic mineral, known for striking sparks and a garlic smell when struck.
mineral
Chalcopyrite
A brassy copper-iron sulfide that is the world's most important copper ore, often showing colorful iridescent tarnish.
mineral
Peacock Ore
A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.
mineral
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
Latite
The fine-grained volcanic equivalent of monzonite, an intermediate lava with nearly equal feldspars and little free quartz.
igneous
Zebra Jasper
A black-and-white striped chalcedony-quartz rock whose bold zebra-like banding makes it a popular ornamental and lapidary stone.
sedimentary
Dragon Vein Agate
A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.
gemstone
Nordmarkite
A light-colored alkali quartz syenite dominated by perthitic feldspar with minor quartz, from the Oslo igneous province of Norway.
igneous
Kiwi Jasper
A speckled green-and-black stone resembling kiwi fruit, technically a quartz-amazonite aggregate rather than true jasper.
mineral
Yellow Jasper
An opaque yellow-to-golden variety of jasper, an iron-stained microcrystalline quartz prized for warm color and durable polish.
gemstone
Sonoran Sunset Jasper
A vivid copper-bearing Mexican stone of red cuprite and green chrysocolla that evokes a desert sunset.
mineral
Black Agate
A deep black variety of banded chalcedony, often closely related to or treated like onyx, used for jewelry and carvings.
gemstone
Sandstone
A clastic sedimentary rock made of cemented sand grains, often quartz, recording ancient beaches, deserts, and rivers.
sedimentary
Apricot Agate
A soft peachy-orange variety of banded chalcedony, naturally iron-tinted or dyed, popular for warm-toned beads and jewelry.
gemstone
Paragonite Schist
A pale, silvery schist dominated by paragonite, the sodium-rich white mica, formed in aluminous metamorphic rocks.
metamorphic
Tiger's Eye
A golden-brown chatoyant quartz with a shimmering silky band of light, formed when quartz replaces fibrous crocidolite.
gemstone
Carnelian
A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.
gemstone
Black Onyx
A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.
gemstone