Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Mexican Lace Agate
A vividly swirling banded agate from northern Mexico with intricate looping patterns in warm reds, golds and creams.
gemstoneSunset Agate
A warmly colored chalcedony agate with reds, oranges, golds, and pinks that blend like the glowing bands of a sunset sky.
gemstone
Red Obsidian
Volcanic glass tinted red by fine iron-oxide inclusions, often blended with black to form mahogany-patterned obsidian.
crystalStone Canyon Jasper
A warm-toned brecciated jasper from central California known for swirling browns, golds, and creams broken by darker seams.
gemstone
Lamprophyre
A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.
igneous
Bohemian Garnet
Small, intensely red chrome-pyrope garnets from the Czech Bohemian region, famous for densely set antique Victorian jewelry.
gemstoneAutumn Jasper
A warm-toned jasper named for its autumn-leaf palette of browns, rust, gold, and cream, popular as soothing earth-tone beads.
mineral
Lotus Jasper
A softly patterned jasper in cream, gray, and tan whose markings can suggest lotus petals, popular for calm, neutral-toned jewelry.
gemstone
Hematite
The principal iron ore, a heavy iron oxide ranging from metallic silver-gray to earthy red, always leaving a tell-tale red-brown streak.
mineral
Andesite
A fine-grained, intermediate volcanic rock common at subduction-zone volcanoes, between basalt and rhyolite in composition.
igneous
Andesine
An intermediate plagioclase feldspar between albite and anorthite, marketed as a red to champagne gemstone, sometimes color-treated.
gemstonePolychrome Jasper
A warm earth-toned jasper from Madagascar in flowing reds, oranges and golds, also called desert jasper, discovered in the early 2000s.
gemstone
Mushroom Tourmaline
A rare mushroom-shaped tourmaline growth habit, typically magnesium-rich dravite/uvite, prized by collectors for its fungus-like cap-and-stem form.
mineral
Mica Schist
A glittery, strongly foliated rock made mostly of aligned mica flakes that split into thin, shiny sheets.
metamorphic
Andradite Garnet
The calcium-iron garnet species, ranging from brilliant green demantoid to golden topazolite and jet-black melanite.
gemstone
Phyllite
A fine-grained foliated metamorphic rock between slate and schist, recognized by its silky silvery sheen and wavy, crinkled surfaces.
metamorphic
Ignimbrite
A rock formed from hot pyroclastic flows, often welded, sometimes containing flattened glass lenses called fiamme.
igneousGondite
A metamorphic rock made chiefly of manganese-rich spessartine garnet and quartz, formed from ancient manganese-bearing sediments.
metamorphic
Uvite
A calcium-magnesium tourmaline that forms in metamorphosed limestones, typically dark green to brown and often in well-formed crystals.
mineral
Pumice
A frothy, lightweight volcanic glass so full of gas bubbles that it can float on water.
igneous
Andesine-Labradorite
An intermediate plagioclase feldspar spanning andesine and labradorite, marketed as a red-to-green gem, much of which is copper-diffusion treated.
gemstone
Paragonite Schist
A pale, silvery schist dominated by paragonite, the sodium-rich white mica, formed in aluminous metamorphic rocks.
metamorphic
Talc-carbonate Rock
A soft metamorphic rock made of talc and magnesite or dolomite, formed by hydrothermal alteration of ultramafic rocks.
metamorphic
Charnockite
A granite-like rock containing orthopyroxene, formed at high temperatures and pressures and often classed with the granulites.
igneous