Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Coral Rock
A porous limestone built from the calcium carbonate skeletons of corals and reef organisms, the lithified remains of ancient or modern reefs.
sedimentary
Latite
The fine-grained volcanic equivalent of monzonite, an intermediate lava with nearly equal feldspars and little free quartz.
igneous
Albite
The sodium end-member of the plagioclase feldspar series, a common white rock-forming mineral and parent of peristerite moonstone.
mineralGreen Sheen Obsidian
Black volcanic glass that flashes a green sheen at certain angles due to light interference off aligned microscopic inclusions.
igneous
Columbite
A black iron-manganese niobate that is a primary ore of niobium, forming a continuous series with tantalite (together called coltan).
mineral
Websterite
A variety of pyroxenite composed of both orthopyroxene and clinopyroxene with little olivine, found in layered intrusions and the mantle.
igneous
Coober Pedy Opal
Australia's classic light-bodied precious opal from Coober Pedy, famed for milky white stones flashing pastel rainbow play-of-color.
gemstone
Jadeite
The rarer and more valuable of the two jade minerals, prized for its translucent emerald-green 'imperial' color and extreme toughness.
gemstone
Turbidite
A graded sedimentary deposit laid down by underwater turbidity currents, recording avalanches of sediment cascading down submarine slopes.
sedimentary
Olenite
A rare aluminum-rich species of the tourmaline group, usually colorless to pale, named for the Olenii Range in Russia's Kola Peninsula.
mineralGary Green Jasper
An Oregon jasper, also called larsonite, of silicified fossil wood showing olive-green fields laced with black dendritic patterns.
mineral
Iceland Spar
A transparent, optical-grade variety of calcite famous for strong double refraction, splitting images and light into two rays.
mineral
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
Rose Quartz
The soft pink, usually cloudy variety of quartz colored by trace titanium or microscopic inclusions, popular for carvings and beads.
crystalKnorringite
A chromium-rich magnesium garnet of the pyrope series that crystallizes in the deep mantle and is a valuable diamond indicator mineral.
mineral
Yellow Jasper
An opaque yellow-to-golden variety of jasper, an iron-stained microcrystalline quartz prized for warm color and durable polish.
gemstone
Metaconglomerate
A conglomerate altered by heat and pressure, often with its rounded pebbles stretched and flattened into elongated lenses.
metamorphic
Mexican Fire Opal
A transparent to translucent opal prized for its glowing orange-to-red body color, mined chiefly in the volcanic highlands of Mexico.
gemstone
Chrome Chalcedony
A vivid green chalcedony colored by chromium, often called mtorolite, resembling chrysoprase but owing its color to chromium rather than nickel.
gemstone
Schorlomite
A lustrous black titanium-rich garnet of the andradite series, found in alkaline igneous rocks like nepheline syenite and ijolite.
mineral
Oregon Sunstone
A copper-bearing labradorite feldspar from Oregon, famous for its range of natural colors and glittery aventurescent copper schiller.
gemstone
Spectrolite
A premium dark Finnish labradorite displaying the full color spectrum of iridescent flashes, prized as one of the most vivid feldspar gems.
gemstone
Melanite Garnet
The titanium-rich black variety of andradite garnet, with a brilliant resinous luster prized for mourning and statement jewelry.
gemstonePurple Sheen Obsidian
Black volcanic glass that reveals a soft purple-to-violet sheen at certain angles, caused by light interference off aligned inclusions.
igneous