Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Ignimbrite
A rock formed from hot pyroclastic flows, often welded, sometimes containing flattened glass lenses called fiamme.
igneousSea Sediment Jasper
A colorful trade-name material, often dyed and reconstituted, sold as jasper; vivid blues and greens are typically artificially enhanced.
mineral
Arkose
A coarse, feldspar-rich sandstone, often pink, that records rapid erosion of granitic source rock under arid conditions.
sedimentary
Radiolarite
A hard, fine-grained siliceous rock built from the microscopic silica skeletons of radiolarians, often forming colorful ribbon-banded cherts.
sedimentary
Potassium Feldspar
The potassium-rich feldspar group - orthoclase, microcline, and sanidine - a major rock-forming mineral often recognized by its salmon-pink color.
mineral
Chrome Chalcedony
A vivid green chalcedony colored by chromium, often called mtorolite, resembling chrysoprase but owing its color to chromium rather than nickel.
gemstoneUmbalite Garnet
A delicate pink to lavender garnet from Tanzania's Umba Valley, a pyrope-spessartine blend often marketed as a soft, light-toned rhodolite.
gemstone
Pisolite
A sedimentary rock built from pea-sized concentric spheres called pisoids, often carbonate but sometimes iron or aluminum-rich.
sedimentary
Prehnite
A translucent yellow-green silicate famous for its botryoidal 'grape' clusters, often hosting needle-like sprays of black epidote.
mineral
Sodalite
A royal-blue feldspathoid mineral with white calcite veining, often confused with lapis lazuli but lacking its golden pyrite flecks.
mineral
Cacholong Opal
An opaque, porcelain-white common opal prized for its milky, pearl-like appearance and high porosity, often carved or beaded.
gemstone
Cordierite Hornfels
A tough, fine-grained contact-metamorphic rock containing cordierite, often spotted, formed by heat from nearby igneous intrusions.
metamorphic
Turquoise
A prized blue to blue-green copper-aluminium phosphate, often veined with dark matrix, treasured for jewelry across many cultures.
mineral
Lamprophyre
A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.
igneous
Brazilian Opal
Precious opal from Brazil, especially the Pedro II area of Piaui, known for bright, often stable crystal and white opal.
gemstone
Pelitic Schist
A schist derived from clay-rich sediments, rich in mica and often bearing index minerals like garnet, staurolite, or kyanite.
metamorphic
Galena
A heavy, lead-grey metallic mineral with perfect cubic cleavage, galena is the world's main ore of lead and often carries silver.
mineral
Opalite
A man-made opalescent glass that glows milky blue in reflected light and warm orange when backlit, often sold as a crystal.
crystalArizona Ruby
Arizona Ruby is a chromium-rich pyrope garnet from Arizona, often gathered from anthills, valued for its intense ruby-like red.
gemstone
Dumortierite
A hard aluminum borosilicate famous for its rich denim-blue color, often forming dense fibrous masses or coloring quartz blue.
mineral
Monazite
A reddish-brown rare-earth phosphate that is a primary ore of cerium, thorium and other rare-earth elements, often found in placer sands.
mineral
Skarn
A calc-silicate rock formed by chemical exchange between magma and carbonate rock, often rich in garnet and economically important ore minerals.
metamorphic
Pele's Tears
Small, smooth, teardrop-shaped beads of basaltic volcanic glass formed from airborne lava droplets, often paired with Pele's hair.
igneous
Cherry Opal
A translucent red opal, closely related to Mexican fire opal, glowing with a warm cherry-red body color often free of play-of-color.
gemstone