Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Limestone
A soft carbonate sedimentary rock made mostly of calcite, often packed with marine fossils and prone to forming caves.
sedimentaryLithographic Limestone
Extremely fine-grained, even-textured limestone famous for lithographic printing and for preserving exquisite fossils like Archaeopteryx.
sedimentary
Oolitic Limestone
Limestone built from tiny rounded ooid grains resembling fish roe, formed in warm, agitated shallow seas.
sedimentary
Dalmatian Stone
A cream-colored feldspar-and-quartz rock peppered with dark spots, named for its resemblance to a Dalmatian dog.
igneous
Oolite
A limestone made of tiny spherical ooids, resembling fish roe, formed in warm, agitated shallow seas.
sedimentary
Coral Rock
A porous limestone built from the calcium carbonate skeletons of corals and reef organisms, the lithified remains of ancient or modern reefs.
sedimentary
Coquina
A soft, porous limestone made of loosely cemented shell and coral fragments, used as a coastal building stone.
sedimentary
Pisolite
A sedimentary rock built from pea-sized concentric spheres called pisoids, often carbonate but sometimes iron or aluminum-rich.
sedimentary
Travertine
A banded, porous limestone deposited by mineral springs, prized as a warm-toned natural building and tile stone.
sedimentaryAsphalt Rock
A porous sedimentary rock naturally saturated with bitumen, dark, tarry-smelling, and historically mined for paving.
sedimentary
Champagne Garnet
A soft brownish-golden garnet named for its champagne color, usually a malaia-type pyrope-spessartine blend prized for warm, neutral tones.
gemstone
Septarian Concretion
A rounded sedimentary nodule cracked internally and filled with veins of yellow calcite, prized for its striking dragon-skin patterning.
sedimentaryPicasso Jasper
A marbled, abstractly patterned stone resembling modern art, technically a metamorphosed limestone rather than a true silica jasper.
metamorphic
Honey Garnet
A warm golden-brown garnet named for its honey color, typically a hessonite grossular variety with a distinctive treacly internal texture.
gemstone
Ruin Marble
A fractured fine-grained limestone whose iron-stained crack networks form natural scenes resembling ruined cities and landscapes.
sedimentary
Blue Calcite
A soft, soothing powder-blue variety of calcite, a common calcium carbonate mineral often sold as gentle tumbled stones.
mineral
Green Calcite
A soft mint-to-apple-green variety of calcite, a common calcium carbonate mineral popular as soothing tumbled stones.
mineral
Ironstone
An iron-rich sedimentary rock, often heavy and rusty-weathering, historically mined as a major source of iron ore.
sedimentaryParticolored Tourmaline
A tourmaline displaying two or more distinct colors in a single crystal, prized for natural color zoning like watermelon and bicolor stones.
gemstone
Green Beryl
Light green beryl colored mainly by iron, distinguished from emerald, which owes its deeper green to chromium or vanadium.
gemstone
Bumblebee Jasper
A vivid yellow-and-black banded stone from Indonesian volcanic vents, colored by sulfur, arsenic minerals and iron oxides, not true jasper.
sedimentary
Mint Green Tourmaline
A soft, refreshing mint-to-seafoam green elbaite tourmaline, lightly colored by iron and prized for clarity and a cool, airy hue.
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.
gemstoneSard
A brownish-red to deep brown variety of chalcedony, closely related to carnelian but darker, colored by iron oxides.
mineral