Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Fireworks Obsidian
Black volcanic glass dotted with radiating spherulite bursts that look like exploding fireworks frozen in the stone.
igneous
Pietersite
A brecciated, chatoyant quartz with swirling blue, gold, and brown fibers that shimmer like a stormy sky.
gemstone
Moonstone
A feldspar gem famous for adularescence, a floating blue-white glow that shimmers across the stone like moonlight.
gemstoneCalico Obsidian
A mottled, multicolored obsidian blending black, brown, grey, and tan patches like a calico cat's patchwork coat.
igneousCloudy Obsidian
Obsidian with a hazy, cloud-like translucency caused by uneven distribution of tiny bubbles or incipient crystallites in the glass.
igneous
Mahogany Obsidian
A natural volcanic glass with rich brown and black mahogany-like swirls created by iron oxide inclusions.
igneousMidnight Lace Obsidian
A black volcanic glass threaded with delicate grey, swirling lace-like bands of flow lines that show beautifully when polished.
igneousAurora Obsidian
A trade name for rainbow-sheen obsidian whose aligned nanoparticles produce shifting aurora-like bands of color.
igneousCat's Eye Aquamarine
Aquamarine that shows a bright moving band of light, or cat's eye, caused by parallel needle-like inclusions when cut as a cabochon.
gemstone
Emerald in Matrix
Natural emerald crystals still embedded in their host rock, prized as mineral specimens that show how the gem grew in place.
gemstone
Sodalite
A royal-blue feldspathoid mineral with white calcite veining, often confused with lapis lazuli but lacking its golden pyrite flecks.
mineral
Morganite Crystal
The natural crystal form of morganite, the manganese-colored pink-to-peach variety of beryl popular in romantic jewelry.
crystal
Emerald Crystal
The natural crystalline form of emerald, the prized green chromium-and-vanadium variety of beryl and the May birthstone.
crystalFlame Obsidian
Black volcanic glass that flashes flame-like bands of iridescent color when light strikes aligned nanoscale inclusions.
igneousLace Obsidian
Black volcanic glass laced with delicate web-like veins of contrasting color, formed by flow banding and fine crystallization.
igneous
Indicolite
The blue variety of tourmaline, a relatively rare and prized color ranging from teal and greenish blue to deep indigo.
gemstone
Aquamarine
The serene blue-to-sea-green variety of beryl, aquamarine is a durable gemstone colored by trace iron and birthstone for March.
gemstone
Azurite
A deep blue copper carbonate mineral that forms in oxidized copper deposits, often alongside green malachite.
mineralMaxixe
A deep blue beryl with a color caused by radiation that fades in light, named after the Maxixe mine in Brazil.
gemstone
Peristerite
A sodium-rich plagioclase moonstone whose fine intergrowth lamellae scatter light into a delicate blue, pigeon-neck sheen.
gemstone
Glaucophane Schist
A blue, high-pressure metamorphic schist rich in glaucophane, the classic rock of subduction zones, also known as blueschist.
metamorphic
Dumortierite
A hard aluminum borosilicate famous for its rich denim-blue color, often forming dense fibrous masses or coloring quartz blue.
mineral
Peacock Ore
A copper-iron sulfide ore famous for its iridescent peacock-like purple and blue tarnish; often sold as treated chalcopyrite.
mineral
Maxixe Aquamarine
A deep blue beryl whose intense color comes from radiation-induced color centers and tends to fade in light, named after the Maxixe mine in Brazil.
gemstone