Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Iris Agate
A banded agate that diffracts transmitted light into rainbow colors when cut thin and backlit, producing a spectacular iridescence.
gemstone
Green Agate
A green-hued banded chalcedony, ranging from natural soft greens to brightly dyed commercial stones.
gemstoneCoyamito Agate
A prized banded agate from Rancho Coyamito in Chihuahua, Mexico, known for eyes, pom-poms and vivid fortification.
gemstone
Flower Agate
A creamy pink-and-white chalcedony from Madagascar containing flower-like plume inclusions that resemble blossoms suspended in stone.
gemstone
Purple Agate
A purple-toned banded chalcedony, sometimes naturally amethystine but frequently produced by dyeing gray agate.
gemstoneZebra Agate
A banded chalcedony agate with bold alternating dark and light stripes resembling zebra markings, sometimes color-enhanced.
gemstone
Kentucky Agate
The official state rock of Kentucky, a banded agate famous for striking deep-red and black fortification patterns.
gemstone
White Agate
A white to grayish banded chalcedony, the natural base color of much agate and the substrate for many dyed stones.
gemstone
Black Agate
A deep black variety of banded chalcedony, often closely related to or treated like onyx, used for jewelry and carvings.
gemstoneBamboo Agate
An agate whose layered, segmented banding resembles the jointed stalks and leaves of bamboo.
gemstone
Sweetwater Agate
A translucent Wyoming chalcedony filled with delicate black manganese dendrites that resemble tiny ferns, moss, or starbursts.
gemstone
Laguna Agate
A highly prized Mexican fortification agate from Chihuahua, famed for vivid red and orange banding with tight, intricate patterns.
gemstone
Sagenite Agate
A chalcedony agate filled with radiating needle-like mineral inclusions, prized for its starburst and spray patterns.
gemstone
Moss Agate
A translucent chalcedony filled with green or brown dendritic mineral inclusions that resemble moss, foliage, or landscapes.
gemstoneCarver Agate
A collectible Oregon plume and scenic agate with feathery red and gold inclusions suspended in translucent chalcedony.
gemstone
Thunderegg Agate
A nodular rhyolite geode-like ball whose plain exterior hides a star-shaped agate or chalcedony core when cut.
gemstone
Landscape Agate
A translucent chalcedony agate whose mineral inclusions form miniature scenes resembling mountains, trees, deserts, and skies.
gemstone
Plume Agate
A translucent agate containing delicate three-dimensional feather- or plant-like plumes of mineral inclusions suspended in chalcedony.
gemstone
Fairburn Agate
The state gemstone of South Dakota, a rare fortification agate known for tight, holly-leaf concentric banding.
gemstone
Grape Agate
Clusters of tiny botryoidal chalcedony spheres resembling bunches of grapes, famously purple, found in Indonesia.
mineral
Banded Iron Formation
Ancient chemically deposited rock of alternating iron-oxide and silica bands recording Earth's early oxygenation and a major iron ore source.
sedimentary
Ruin Agate
A fractured and re-cemented agate whose angular broken bands resemble crumbling walls and ruined cityscapes when polished.
gemstone
Blood Agate
A deep red banded agate colored by iron oxides, valued as a vivid red lapidary and jewelry stone.
gemstoneColdwater Agate
A glacially transported agate found in Midwestern gravels, named for the Coldwater area, showing banded chalcedony patterns.
gemstone