Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Black Moonstone
A dark gray-to-black feldspar variety of moonstone that shows blue and white adularescent flash against a smoky body.
gemstone
Gneiss
A high-grade metamorphic rock defined by alternating light and dark mineral bands, formed under intense heat and pressure.
metamorphic
Tourmaline Schist
A foliated schist threaded with black tourmaline (schorl) needles, marking boron-rich metamorphic or metasomatic conditions.
metamorphicZebra Agate
A banded chalcedony agate with bold alternating dark and light stripes resembling zebra markings, sometimes color-enhanced.
gemstoneOrca Agate
A bold black-and-white banded chalcedony named for its orca-like coloring, popular as carvings and statement jewelry.
gemstone
Snowflake Obsidian
A black volcanic glass speckled with gray-white cristobalite snowflakes, formed as obsidian begins to crystallize.
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
White Opal
The most common precious opal, with a pale milky body that shows softer pastel flashes of play-of-color throughout.
gemstone
White Beryl
The colorless to milky-white variety of beryl, known mineralogically as goshenite and once used to imitate diamond and other gems.
gemstone
White Topaz
A colorless, transparent variety of topaz valued as an affordable, hard, brilliant alternative to diamond in jewelry.
gemstone
Howlite
A white, porous borate mineral webbed with gray-black veins, widely dyed to imitate turquoise and other stones.
mineralWhiteschist
A rare high-pressure metamorphic schist defined by the diagnostic assemblage of talc plus kyanite, often pale and silvery.
metamorphic
Australian Opal
Opal from Australia, the world's leading source of precious opal, ranging from white and crystal to prized black and boulder types.
gemstone
Onyx
A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.
gemstone
White Agate
A white to grayish banded chalcedony, the natural base color of much agate and the substrate for many dyed stones.
gemstoneBlack Onyx
A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.
gemstone
Black Shale
Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.
sedimentary
Black Opal
The rarest and most valuable opal, with a dark body tone that makes its flashing rainbow play-of-color blaze brilliantly.
gemstone
White Garnet
The rare colorless-to-white grossular garnet, also called leuco garnet, prized by collectors for its purity and unusual lack of color.
gemstone
Khondalite
A high-grade metamorphic gneiss of garnet, sillimanite, quartz, and graphite, derived from ancient aluminous sediments.
metamorphic
Black Garnet
An opaque black garnet — typically titanium-bearing melanite andradite — historically cut for mourning and Victorian jewelry.
gemstone
Black Agate
A deep black variety of banded chalcedony, often closely related to or treated like onyx, used for jewelry and carvings.
gemstone
Tree Agate
A white chalcedony filled with green or black dendritic, tree-like mineral inclusions that resemble ferns or moss frozen in stone.
gemstone
White Obsidian
A pale, partly crystallized volcanic glass; genuinely white obsidian is uncommon and usually reflects devitrification or spherulitic growth in the glass.
igneous