Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Yowah Nut Opal
Small ironstone concretions from Yowah, Queensland, whose hollow or veined centers hold brilliant precious boulder opal.
gemstone
Ferricrete
Hard surface crust formed when iron oxides cement soil and sediment into a rusty, durable duricrust in tropical and weathered terrains.
sedimentaryRiband Agate
A banded chalcedony with straight, ribbon-like parallel layers, often cut across the bands for striking striped cabochons.
gemstone
Tiger Iron
A banded combination rock of golden tiger's eye, red jasper, and metallic hematite, formed in ancient iron deposits.
metamorphic
Mookaite
A vivid Australian jasper-like silica stone in earthy reds, yellows, and purples, formed from silicified radiolarian sediment.
mineralStripe Obsidian
Obsidian crossed by parallel flow bands of differing color, formed as layers of lava with slightly different compositions froze into glass.
igneous
Quilpie Opal
Boulder opal from the Quilpie district of Queensland, Australia, with bright color set in dark ironstone matrix.
gemstoneWonderstone
A banded rhyolitic volcanic rock with swirling tan, red, and yellow iron-oxide layers prized as a decorative picture stone.
igneous
Rhyolite
A fine-grained, silica-rich volcanic rock that is the extrusive equivalent of granite, often pale, banded, or flow-textured.
igneous
Mahogany Obsidian
A natural volcanic glass with rich brown and black mahogany-like swirls created by iron oxide inclusions.
igneousLace Obsidian
Black volcanic glass laced with delicate web-like veins of contrasting color, formed by flow banding and fine crystallization.
igneousPigeon Blood Agate
A richly colored red banded agate prized by lapidaries for its deep crimson-to-brown tones reminiscent of pigeon's blood.
gemstoneBamboo Agate
An agate whose layered, segmented banding resembles the jointed stalks and leaves of bamboo.
gemstone
Lake Superior Agate
A glacier-transported banded agate from the Lake Superior region, colored by iron into rich reds and oranges, and Minnesota's state gemstone.
gemstone
Brown Obsidian
Obsidian colored brown by iron oxide inclusions, frequently banded or swirled with black as in mahogany obsidian.
igneousFlame Obsidian
Black volcanic glass that flashes flame-like bands of iridescent color when light strikes aligned nanoscale inclusions.
igneousReptile Jasper
A green-and-black mottled jasper whose scale-like patterning resembles reptile skin, often linked to Kambaba and crocodile jaspers.
mineralSesame Jasper
A finely speckled pale jasper trade stone named for its sesame-seed-like flecks, closely related to Kiwi Jasper.
mineral
Flower Jasper
A jasper whose radiating mineral clusters form flower-like rosettes scattered across an earthy background.
mineralFeather Jasper
A jasper marked with soft feather- or plume-like mineral inclusions that drift through a pale silica body.
mineral
Leopard Skin Jasper
A spotted jasper-rhyolite patterned with leopard-like rings and ovals, valued as an earthy ornamental and lapidary stone.
sedimentary
Pelitic Schist
A schist derived from clay-rich sediments, rich in mica and often bearing index minerals like garnet, staurolite, or kyanite.
metamorphicOrca Agate
A bold black-and-white banded chalcedony named for its orca-like coloring, popular as carvings and statement jewelry.
gemstoneSilver Leaf Jasper
A gray-toned jasper with swirling cream, black, and brown leaf-like patterns, sometimes with druzy or agate pockets.
mineral