Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Black Shale
Dark, organic-rich fine-grained sedimentary rock formed in oxygen-poor waters, often a source rock for oil and gas.
sedimentaryFancy Jasper
A soft-toned, multicolored jasper with swirling green, mauve, and cream patterns, popular and affordable in the bead trade.
sedimentary
Staurolite Schist
A mica schist studded with brown staurolite porphyroblasts, sometimes forming the cross-shaped twins known as fairy stones.
metamorphicScenic Agate
A translucent agate whose mineral inclusions resemble miniature landscapes of trees, hills, and horizons within the stone.
gemstonePaintbrush Jasper
A scenic jasper whose flowing streaks of warm color resemble strokes left by a loaded paintbrush.
mineral
Neon Blue Tourmaline
An intensely glowing copper-bearing tourmaline whose electric neon-blue color makes it one of the most valuable gems in the world.
gemstone
Wacke
A poorly sorted, muddy sandstone with abundant clay matrix between its grains, typically dark and deposited by turbidity currents.
sedimentary
Snake Skin Agate
A chalcedony with a distinctive scaly, reptile-skin surface texture, typically in pale tan, pink, and gray tones.
gemstone
Blue Goldstone
A man-made glittering glass colored deep blue with cobalt and studded with tiny copper crystals that mimic a starry night sky.
gemstone
Idaho Star Garnet
Idaho's official state gem: a dark almandine garnet showing a four- or rare six-rayed star from oriented rutile inclusions.
gemstone
Silver Sheen Obsidian
Black volcanic glass displaying a silvery shimmer from light reflecting off aligned microscopic gas bubbles trapped in the obsidian.
crystal
Shungite
A rare black carbon-rich rock from Russia, noted for containing fullerenes and ranging from dull mineralized stone to lustrous noble shungite.
sedimentary
Anthracite
The highest-rank coal, a hard, lustrous black rock that burns cleanly with little smoke and high heat output.
metamorphicReptile Jasper
A green-and-black mottled jasper whose scale-like patterning resembles reptile skin, often linked to Kambaba and crocodile jaspers.
mineralSwazi Lace Agate
A swirling, intricately banded lace agate from Eswatini (Swaziland) in soft greys, blues and lavenders with delicate folded patterns.
gemstone
Dendritic Agate
A translucent chalcedony decorated with branching, fern-like manganese or iron oxide inclusions resembling tiny plants.
mineral
Turritella Agate
A brown fossiliferous chalcedony packed with spiral freshwater snail shells, technically agatized fossil rock from Wyoming.
sedimentary
Star Garnet
A rare almandine garnet that displays a four- or six-rayed star (asterism) from oriented rutile inclusions; the state gem of Idaho.
gemstone
Bloodstone
A dark green chalcedony speckled with blood-red spots of iron oxide, traditionally known as heliotrope.
gemstone
Mexican Lace Agate
A vividly swirling banded agate from northern Mexico with intricate looping patterns in warm reds, golds and creams.
gemstone
Golden Rainbow Obsidian
Black obsidian that displays a golden-to-rainbow iridescent sheen caused by aligned microscopic inclusions reflecting light.
igneousRoyal Sahara Jasper
A warm desert-toned picture jasper trade stone with sandy tan, gold, and brown swirls evoking Saharan dunes.
mineral
Biggs Jasper
A classic Oregon picture jasper showing layered tan, brown, and blue-grey scenes resembling desert landscapes and canyons.
mineralStarry Night Jasper
A dark jasper trade stone speckled with pale flecks resembling a starry night sky, valued for its cosmic appearance.
mineral