Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Geode
A hollow rock nodule whose interior cavity is lined with inward-pointing crystals such as quartz, amethyst, or calcite.
mineralPolyhedroid Agate
A rare agate that forms naturally with flat polygonal faces and angular geometric shapes rather than the usual rounded nodule.
gemstone
Thunderegg Agate
A nodular rhyolite geode-like ball whose plain exterior hides a star-shaped agate or chalcedony core when cut.
gemstone
Brazilian Agate
Abundant banded chalcedony from southern Brazil, the world's main source of agate slices and dyed agate products.
gemstone
Seam Agate
Agate that forms in flat cracks or veins of host rock rather than rounded nodules, producing straight, parallel banding.
gemstoneOrca Agate
A bold black-and-white banded chalcedony named for its orca-like coloring, popular as carvings and statement jewelry.
gemstone
Tube Agate
A chalcedony agate containing hollow or mineral-filled tubes that appear as rods, circles, or pipes depending on the angle of the cut.
gemstone
Moss Agate
A translucent chalcedony filled with green or brown dendritic mineral inclusions that resemble moss, foliage, or landscapes.
gemstone
Plume Agate
A translucent agate containing delicate three-dimensional feather- or plant-like plumes of mineral inclusions suspended in chalcedony.
gemstone
Eye Agate
A chalcedony agate marked by round, concentric ring patterns that resemble eyes when cut and polished.
gemstoneCarver Agate
A collectible Oregon plume and scenic agate with feathery red and gold inclusions suspended in translucent chalcedony.
gemstoneApricot Agate
A soft peachy-orange variety of banded chalcedony, naturally iron-tinted or dyed, popular for warm-toned beads and jewelry.
gemstone
Laguna Agate
A highly prized Mexican fortification agate from Chihuahua, famed for vivid red and orange banding with tight, intricate patterns.
gemstone
Tree Agate
A white chalcedony filled with green or black dendritic, tree-like mineral inclusions that resemble ferns or moss frozen in stone.
gemstoneFrost Agate
A pale chalcedony agate with cloudy, frost-like white patterning suggesting frost on a window or icy crystalline textures.
gemstone
Flame Agate
A chalcedony agate with red, orange, and yellow plume or banding patterns that rise like dancing flames within the stone.
gemstoneSunset Agate
A warmly colored chalcedony agate with reds, oranges, golds, and pinks that blend like the glowing bands of a sunset sky.
gemstone
Black Agate
A deep black variety of banded chalcedony, often closely related to or treated like onyx, used for jewelry and carvings.
gemstoneMocha Agate
A pale translucent chalcedony threaded with brown-black manganese and iron dendrites that mimic tiny ferns, mosses or landscapes.
gemstone
Banded Agate
The classic agate defined by concentric or parallel bands of chalcedony in varied colors, the archetype of all agate varieties.
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.
gemstone
Feather Agate
A translucent chalcedony agate containing delicate, feather- or plume-shaped mineral inclusions that branch like soft feathers.
gemstoneRegency Rose Agate
A prized plume agate with rose-pink and red feathery inclusions suspended in clear chalcedony, from the western U.S.
gemstonePriday Plume Agate
A classic Oregon plume agate from the Priday Ranch beds, showing feathery mineral plumes suspended in translucent chalcedony.
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