Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Harzburgite
A depleted mantle peridotite of olivine and orthopyroxene, the refractory residue left after basaltic melt is extracted from the mantle.
igneousBurgundy Tourmaline
A deep wine-red to maroon tourmaline colored by manganese, a rich darker-toned member of the red-pink rubellite family.
gemstoneKnorringite
A chromium-rich magnesium garnet of the pyrope series that crystallizes in the deep mantle and is a valuable diamond indicator mineral.
mineral
White Obsidian
A pale, partly crystallized volcanic glass; genuinely white obsidian is uncommon and usually reflects devitrification or spherulitic growth in the glass.
igneousMaxixe
A deep blue beryl with a color caused by radiation that fades in light, named after the Maxixe mine in Brazil.
gemstoneGrape Garnet
A trademarked deep purple-red rhodolite garnet from India, named for its rich grape-like color from the pyrope-almandine series.
gemstoneLeuco Garnet
The rare colorless variety of grossular garnet, a near-flawless transparent gem free of the iron and chromium that color most garnets.
gemstone
Pink Emerald
A trade name sometimes used for pink beryl (morganite), the manganese-colored rose-to-peach variety of the emerald mineral.
gemstone
Trapiche Emerald
A rare emerald showing a six-spoked star pattern of dark inclusions, named after the spokes of a sugar-mill wheel.
gemstone
Phosphorite
Phosphate-rich sedimentary rock, the world's main source of phosphorus for fertilizers, formed in nutrient-rich marine settings.
sedimentary
Pumpkin Obsidian
An orange-to-rust colored variety of natural volcanic glass whose warm tone comes from iron oxide staining within the obsidian.
igneous
Shattuckite
A rare deep-blue copper silicate mineral, often fibrous or massive, named for the Shattuck Mine in Arizona and prized by collectors.
mineral
Imperial Garnet
A trade name for high-brilliance golden grossular-andradite (grandite) garnet, most associated with the Mali deposits of West Africa.
gemstone
Bixbite
An old trade name for red beryl, the extremely rare manganese-colored beryl from Utah, now largely replaced by the term red beryl.
gemstone
Iolite
The gem variety of cordierite, famous for strong pleochroism that shifts from violet-blue to near-colorless.
gemstone
White Moonstone
The classic moonstone: a milky-white feldspar showing the prized floating blue-to-silver adularescent glow that gives the gem its name.
gemstone
Schorlomite
A lustrous black titanium-rich garnet of the andradite series, found in alkaline igneous rocks like nepheline syenite and ijolite.
mineralRed Emerald
A marketing name for red beryl, the rare manganese-colored beryl from Utah, evoking emerald to convey its prestige and rarity.
gemstone
Lithic Sandstone
A sandstone in which the dominant grains are fragments of pre-existing rocks rather than single minerals, signaling rapid erosion nearby.
sedimentary
Limburgite
A dark, glass-rich volcanic rock of olivine and augite phenocrysts set in a feldspar-free glassy groundmass, named from the Kaiserstuhl region.
igneous
Troctolite
A mafic plutonic rock of plagioclase and olivine whose mottled appearance earned it the nickname 'troutstone'.
igneous
Pyrrhotite
A bronze-colored iron sulfide notable for being the most magnetic of the common sulfide minerals and an important nickel host.
mineral
Morion Quartz
The darkest, near-opaque black variety of smoky quartz, colored by natural radiation acting on trace aluminum.
crystal
Morganite Crystal
The natural crystal form of morganite, the manganese-colored pink-to-peach variety of beryl popular in romantic jewelry.
crystal