Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Kalahari Jasper
An African picture jasper from the Kalahari region with warm desert-toned banding evoking dunes and savanna.
mineral
Rutilated Quartz
Clear or smoky quartz threaded with golden to reddish needles of rutile, also poetically called Venus hair stone.
crystal
Cathedral Quartz
Quartz with a stepped, multi-pointed structure of parallel side crystals resembling the spires of a cathedral.
crystal
Mustard Jasper
A warm mustard-to-ochre yellow jasper colored by iron, valued by lapidaries for its rich, earthy golden tone.
gemstone
Dragon Blood Jasper
A green-and-red ornamental stone of epidote and red piemontite or iron oxide, named for its dragon-skin coloring; not a true jasper.
metamorphic
Dumortierite Quartz
Quartz colored blue by inclusions of the mineral dumortierite, giving a denim-like blue ornamental stone harder than dumortierite alone.
gemstone
Tourmalinated Quartz
Clear or milky quartz threaded with black needles of tourmaline (schorl), combining quartz clarity with dramatic dark inclusions.
crystal
Cobra Jasper
A banded jasper with cream, tan, and brown layers resembling snakeskin, often sourced from Madagascar.
mineral
Bamboo Agate
An agate whose layered, segmented banding resembles the jointed stalks and leaves of bamboo.
gemstone
Crowley Ridge Agate
Agate found in the gravels of Crowley's Ridge in northeastern Arkansas, a stream-transported banded chalcedony.
gemstone
Cave Creek Jasper
An opaque jasper from the Cave Creek area of Arizona, prized for earthy mottled and banded patterns in warm desert tones.
mineral
Sard
A brownish-red to deep brown variety of chalcedony, closely related to carnelian but darker, colored by iron oxides.
mineral
Bird's Eye Jasper
A microcrystalline quartz jasper marked by small concentric ring or eye patterns that resemble the eyes of birds.
mineral
Coldwater Agate
A glacially transported agate found in Midwestern gravels, named for the Coldwater area, showing banded chalcedony patterns.
gemstone
Cathedral Agate
A banded agate whose internal structures resemble cathedral spires, arches, or a city skyline of towers and pinnacles.
gemstone
Brecciated Jasper
A jasper made of angular fragments naturally cemented back together, typically showing red and brown pieces in a quartz matrix.
sedimentary
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
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
Cherry Creek Jasper
A landscape-patterned Chinese jasper prized for warm cherry-red, cream, and green bands resembling painted scenery.
mineral
Bloodstone Jasper
A dark green jasper-chalcedony speckled with red iron-oxide spots, classically known as bloodstone or heliotrope.
mineral
Honey Agate
A warm golden to amber translucent chalcedony agate whose color and glow resemble honey, sometimes with banding.
gemstone
Sunset Agate
A warmly colored chalcedony agate with reds, oranges, golds, and pinks that blend like the glowing bands of a sunset sky.
gemstone
Flame Agate
A chalcedony agate with red, orange, and yellow plume or banding patterns that rise like dancing flames within the stone.
gemstone
Brown Obsidian
Obsidian colored brown by iron oxide inclusions, frequently banded or swirled with black as in mahogany obsidian.
igneous