Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Australian Opal
Opal from Australia, the world's leading source of precious opal, ranging from white and crystal to prized black and boulder types.
gemstoneParticolored Tourmaline
A tourmaline displaying two or more distinct colors in a single crystal, prized for natural color zoning like watermelon and bicolor stones.
gemstone
Watermelon Tourmaline
A striking color-zoned tourmaline with a pink center and green rind, resembling a slice of watermelon when cut across the crystal.
gemstone
Tourmaline
A boron-rich silicate gemstone group famous for occurring in every color of the rainbow, sometimes several within a single crystal.
gemstone
Cactus Quartz
A South African quartz whose central crystal is coated in a cactus-like crust of tiny secondary points, also called spirit quartz.
crystal
Sulfur
A bright yellow native element mineral that forms around volcanic vents and hot springs and burns with a blue flame.
mineral
Labradorite
A plagioclase feldspar famous for labradorescence, a dramatic flash of iridescent blue, green, and gold across a dark gray stone.
mineral
Bornite
A copper iron sulfide famous for its vivid iridescent purple-blue tarnish, the classic peacock ore and a copper ore.
mineralCarrara Marble
A famous white to blue-grey Italian marble from Carrara, prized for centuries by sculptors and architects for its purity and fine grain.
metamorphic
Peacock Ore
A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.
mineralGrandite Garnet
Grandite is an intermediate garnet between grossular and andradite, common in skarns and prized for vivid green to golden crystals.
mineral
Garnet Schist
A shiny, foliated schist studded with red garnet crystals that grew during medium-grade regional metamorphism.
metamorphic
Hornblende Schist
A dark, foliated schist rich in needle-like hornblende crystals, formed by metamorphism of mafic igneous rocks.
metamorphic
Stibnite
Stibnite is the chief ore of antimony, famous for its dramatic clusters of bladed, silvery-gray metallic crystals.
mineral
Marble
A metamorphosed limestone of interlocking calcite crystals, prized for sculpture and architecture for its workability and polish.
metamorphic
Iolite
The gem variety of cordierite, famous for strong pleochroism that shifts from violet-blue to near-colorless.
gemstone
Montana Moss Agate
A translucent chalcedony from Montana filled with black and red dendritic inclusions that look like moss, ferns, or scenic landscapes.
gemstone
Turritella Agate
A brown fossiliferous chalcedony packed with spiral freshwater snail shells, technically agatized fossil rock from Wyoming.
sedimentaryDragon Vein Agate
A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.
gemstone
Ruby in Zoisite
A striking rock of green zoisite studded with red-pink ruby crystals and black hornblende, also called anyolite.
metamorphicMulticolor Tourmaline
Tourmaline crystals displaying two or more distinct colors at once, including the famous pink-and-green watermelon variety.
gemstone
Hausmannite
A brownish-black manganese oxide and important manganese ore, forming pseudo-octahedral crystals with a chestnut-brown streak.
mineral
Bismuthinite
A soft lead-gray bismuth sulfide that is an important ore of bismuth, forming metallic needle-like and bladed crystals.
mineral
Pyromorphite
A lead phosphate secondary mineral known for barrel-shaped green to yellow crystals formed in oxidized lead deposits.
mineral