Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Greenschist
A green, foliated low-grade metamorphic rock colored by chlorite, actinolite, and epidote, marking the greenschist metamorphic facies.
metamorphic
Ruin Marble
A fractured fine-grained limestone whose iron-stained crack networks form natural scenes resembling ruined cities and landscapes.
sedimentary
Dendritic Agate
A translucent chalcedony decorated with branching, fern-like manganese or iron oxide inclusions resembling tiny plants.
mineral
Mariposite
A green, gold-associated metamorphic rock made of chrome-rich mica and quartz, named for Mariposa County in California's gold country.
metamorphic
Loess
A loose, wind-blown silt deposit, typically buff-colored and very fertile, that forms thick blankets and stands in steep cliffs.
sedimentary
Verdite
A rich green, fuchsite-rich metamorphic rock from southern Africa, prized as a carving and ornamental stone.
metamorphic
Porphyritic Obsidian
Natural volcanic glass speckled with embedded mineral crystals (phenocrysts) such as feldspar or cristobalite that grew before the lava chilled.
igneous
Raspberry Garnet
A vivid pinkish-red rhodolite garnet named for its raspberry color, a bright pyrope-almandine blend popular in jewelry.
gemstone
Guano
An accumulated deposit of bird or bat droppings rich in nitrogen and phosphate, historically a prized natural fertilizer.
sedimentary
Snowflake Obsidian
A black volcanic glass speckled with gray-white cristobalite snowflakes, formed as obsidian begins to crystallize.
igneous
Silver Sheen Obsidian
Black volcanic glass displaying a silvery shimmer from light reflecting off aligned microscopic gas bubbles trapped in the obsidian.
crystal
Picture Jasper
An opaque brown chalcedony whose iron-stained banding mimics deserts, dunes, and distant mountain skylines.
mineral
Mica Schist
A glittery, strongly foliated rock made mostly of aligned mica flakes that split into thin, shiny sheets.
metamorphic
Fire Obsidian
A rare obsidian showing brilliant fiery iridescence caused by thin nanolayers of magnetite crystals diffracting light within the glass.
crystalRainforest Jasper
An Australian green rhyolite with eye-like orbs and earthy patterns marketed as jasper, evoking dense rainforest foliage.
igneous
Aquamarine Crystal
The blue iron-bearing variety of beryl, forming clear hexagonal crystals prized both as specimens and as a March birthstone gem.
crystal
Paragonite Schist
A pale, silvery schist dominated by paragonite, the sodium-rich white mica, formed in aluminous metamorphic rocks.
metamorphic
Golden Rainbow Obsidian
Black obsidian that displays a golden-to-rainbow iridescent sheen caused by aligned microscopic inclusions reflecting light.
igneous
Blueschist
A blue-hued, high-pressure metamorphic schist colored by the amphibole glaucophane, formed in cold, deep subduction zones.
metamorphic
Larvikite
A Norwegian intrusive rock whose feldspar crystals flash silvery-blue, widely used as blue pearl granite countertops.
igneousPigeon Blood Agate
A richly colored red banded agate prized by lapidaries for its deep crimson-to-brown tones reminiscent of pigeon's blood.
gemstone
Bituminous Shale
A dark, organic-rich shale loaded with kerogen and bitumen that can yield oil and gas, often finely laminated and combustible.
sedimentary
Yellow Agate
A yellow to golden banded chalcedony colored by iron, ranging from natural honey tones to dyed commercial stones.
gemstone
Aquamarine
The serene blue-to-sea-green variety of beryl, aquamarine is a durable gemstone colored by trace iron and birthstone for March.
gemstone