Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Picture Jasper
An opaque brown chalcedony whose iron-stained banding mimics deserts, dunes, and distant mountain skylines.
mineralFrost Agate
A pale chalcedony agate with cloudy, frost-like white patterning suggesting frost on a window or icy crystalline textures.
gemstone
Phyllite
A fine-grained foliated metamorphic rock between slate and schist, recognized by its silky silvery sheen and wavy, crinkled surfaces.
metamorphicColdwater Agate
A glacially transported agate found in Midwestern gravels, named for the Coldwater area, showing banded chalcedony patterns.
gemstone
Honey Agate
A warm golden to amber translucent chalcedony agate whose color and glow resemble honey, sometimes with banding.
gemstoneZebra Agate
A banded chalcedony agate with bold alternating dark and light stripes resembling zebra markings, sometimes color-enhanced.
gemstone
Flame Agate
A chalcedony agate with red, orange, and yellow plume or banding patterns that rise like dancing flames within the stone.
gemstoneSlate
A fine-grained, low-grade metamorphic rock that splits into flat sheets along slaty cleavage, long used for roofing and flooring.
metamorphic
Feather Agate
A translucent chalcedony agate containing delicate, feather- or plume-shaped mineral inclusions that branch like soft feathers.
gemstonePigeon Blood Agate
A richly colored red banded agate prized by lapidaries for its deep crimson-to-brown tones reminiscent of pigeon's blood.
gemstone
Cathedral Agate
A banded agate whose internal structures resemble cathedral spires, arches, or a city skyline of towers and pinnacles.
gemstonePolyhedroid Agate
A rare agate that forms naturally with flat polygonal faces and angular geometric shapes rather than the usual rounded nodule.
gemstone
Shadow Agate
A banded agate that displays a moving shadow or flash across its surface when tilted under light, caused by closely spaced parallel bands.
gemstoneCloud Agate
A chalcedony agate with soft, billowing cloud-like masses of gray and white suspended in a translucent body.
gemstoneExotica Jasper
Also called Sci-Fi Jasper, a Mexican jasper-rhyolite with swirling abstract patterns in cream, tan, gray, pink, and green.
gemstone
Teepee Canyon Agate
A fortification agate from the Black Hills of South Dakota, known for tight, colorful banding closely related to the famous Fairburn agate.
gemstone
Calcarenite
Sand-grained limestone composed of carbonate particles such as shell fragments and ooids cemented into a calcite rock.
sedimentary
Sweetwater Agate
A translucent Wyoming chalcedony filled with delicate black manganese dendrites that resemble tiny ferns, moss, or starbursts.
gemstoneSunset Opal
An opal with warm sunset hues of orange, amber, and red, prized for its glowing fiery body color reminiscent of dusk skies.
gemstone
Green Jasper
An opaque green variety of chalcedony quartz colored by iron and chlorite-group inclusions, prized as a durable carving and cabochon stone.
mineral
Bloodstone Jasper
A dark green jasper-chalcedony speckled with red iron-oxide spots, classically known as bloodstone or heliotrope.
mineral
Black Jasper
A dense, opaque black variety of microcrystalline quartz historically used as a touchstone for testing precious metals.
mineralNoreena Jasper
A rare Australian jasper from the Pilbara with bold red, yellow, and black abstract patterns, prized by collectors.
mineralMustard Tourmaline
A warm mustard to brownish-yellow tourmaline, colored by iron or manganese, sitting between yellow and brown dravite tones.
gemstone