Rock Library
217 specimens and counting — a new one every day. See today’s rock, or browse by type.
Igneous
Obsidian
“Nature's volcanic glass”
Granite
“The backbone of continents”
Basalt
“The floor of the ocean”
Pumice
“The rock that floats”
Rhyolite
“Granite's volcanic twin”
Diorite
“Salt-and-pepper plutonic rock”
Andesite
“The subduction zone signature”
Gabbro
“The deep ocean's dark heart”
Pegmatite
“Home of giant crystals”
Tuff
“Volcanic ash turned to stone”
Scoria
“Dark, bubbly lava rock”
Peridotite
“Mantle material exposed”
Komatiite
“Lava from a hotter Earth”
Dacite
“The volcanic middle child”
Phonolite
“The rock that rings like a bell”
Syenite
“Granite's feldspar-rich cousin”
Obsidian (Mahogany)
“Volcanic glass with tiger stripes”
Larvikite
“Norway's shimmering moonstone rock”
Nepheline Syenite
“Silica-poor and industry-essential”
Carbonatite
“The strangest lava on Earth”
Kimberlite
“The diamond delivery system”
Lamprophyre
“The dark dyke intruder”
Trachyte
“The rough-textured lava rock”
Dunite
“Pure olivine from the deep mantle”
Ignimbrite
“Welded from fiery volcanic clouds”
Rhomb Porphyry
“Diamond-shaped crystals in lava”
Aplite
“The fine-grained granite vein”
Norite
“Gabbro's pyroxene-rich twin”
Harzburgite
“A slice of the upper mantle”
Trondhjemite
“The pale granite of the early Earth”
Diabase
“The hard rock of ancient sills and dykes”
Monzonite
“Halfway between granite and gabbro”
Latite
“The volcanic equivalent of monzonite”
Essexite
“The dark alkaline intruder”
Picrite
“Olivine-loaded volcanic lava”
Basanite
“Dark lava with a hint of olivine”
Pantellerite
“The most extreme volcanic glass”
Wehrlite
“Olivine and clinopyroxene from the deep”
Mugearite
“The rare sodium-rich lava”
Nephelinite
“Ultra-alkaline lava from the deep”
Tonalite
“The quartz-rich granite of mountain cores”
Anorthosite
“The rock of the Moon's bright highlands”
Boninite
“Lava born from a newborn subduction zone”
Granodiorite
“The most common plutonic rock on Earth”
Comendite
“Peralkaline rhyolite from rift zones”
Hawaiite
“The islands' signature dark lava”
Shonkinite
“Dark, potassium-rich, and rare”
Tephrite
“Ash-gray alkaline lava”
Leucitite
“Potassium-rich lava with white crystal eyes”
Obsidian (Snowflake)
“Volcanic glass with crystal blooms”
Troctolite
“Spotted like a trout”
Ijolite
“Nepheline and pyroxene from alkaline depths”
Chromitite
“Layers of pure chromium ore”
Minette
“A lamprophyre rich in biotite”
Lherzolite
“The typical upper mantle rock”
Felsite
“Fine-grained and light-colored volcanic rock”
Jacupirangite
“Dark pyroxenite from alkaline complexes”
Sedimentary
Limestone
“Built from ancient seas”
Sandstone
“Cemented grains of time”
Shale
“Earth's most common sedimentary rock”
Conglomerate
“Nature's concrete”
Chalk
“A billion tiny shells”
Travertine
“Hot spring architecture”
Flint
“Spark of civilization”
Coquina
“A fortress of shells”
Dolostone
“Limestone's magnesium cousin”
Chert
“Silica from the seafloor”
Diatomite
“A rock made of glass skeletons”
Rock Salt (Halite)
“The edible rock”
Novaculite
“The razor stone”
Siltstone
“Finer than sand, coarser than clay”
Mudstone
“Earth's quiet record keeper”
Breccia
“A mosaic of broken fragments”
Arkose
“The feldspar-rich sandstone”
Claystone
“The finest sediment, solidified”
Marl
“Where clay meets calcium”
Graywacke
“The turbidity current survivor”
Ironstone
“Sediment stained with iron”
Phosphorite
“Ancient sea beds feeding modern farms”
Tillite
“A glacier's fossilized footprint”
Oolitic Limestone
“Stone made of tiny pearls”
Evaporite
“The residue of vanished seas”
Tufa
“Limestone built by springs and streams”
Lignite
“Coal's youngest form”
Chalk (Red)
“Iron-stained microscopic shells”
Radiolarite
“Built from microscopic glass skeletons”
Bone Bed
“A graveyard turned to stone”
Oil Shale
“Locked-in liquid energy”
Caliche
“Desert cement layer”
Septarian Nodule
“Cracked mud ball filled with crystals”
Laterite
“Tropical soil turned to brick”
Gypsum Rock
“From ancient seas to modern walls”
Coquina (Dense)
“Compacted shell concrete”
Diatomaceous Earth
“A rock made of tiny glass fossils”
Greensand
“Sand colored by the sea”
Flysch
“Deep-sea sediment from colliding continents”
Wackestone
“Mud-supported fossil limestone”
Boundstone
“Reef rock built by living organisms”
Chalk (Nummulitic)
“Coin-shaped fossils that built the pyramids”
Biogenic Chert
“Silica from a billion tiny lives”
Sapropel
“Black ooze from oxygen-starved seas”
Chalk (Writing)
“Classroom chalk from ancient seas”
Loess
“Wind-blown dust turned to stone”
Bauxite
“The aluminum ore that looks like red clay”
Rudstone
“Coarse fossil rubble from ancient reefs”
Spongolite
“Stone made of ancient sponge needles”
Chalk (Phosphatic)
“Enriched by ancient ocean upwelling”
Turbidite
“Graded layers from underwater avalanches”
Cataclastic Breccia
“Fault-shattered rock cemented anew”
Stylolitic Limestone
“Limestone with pressure-dissolved seams”
Banded Iron Formation
“Ancient rust from Earth's first oxygen”
Metamorphic
Slate
“The original chalkboard”
Marble
“Sculptor's dream stone”
Gneiss
“Banded beauty under pressure”
Quartzite
“Sandstone reforged”
Schist
“Sheets of shimmer”
Phyllite
“Between slate and schist”
Eclogite
“Jewels from the mantle”
Hornfels
“Baked by magma's touch”
Serpentinite
“The snake-skinned rock”
Migmatite
“Where rock begins to melt”
Blueschist
“Crushed at the bottom of the sea”
Amphibolite
“Dark, tough, and ancient”
Mylonite
“Crushed under pressure, beautifully streaked”
Granulite
“Forged in Earth's deep crust”
Skarn
“Where magma meets limestone”
Greenschist
“Metamorphism's green signature”
Soapstone
“Soft enough to carve, tough enough to last”
Whiteschist
“Ultra-high-pressure rarity”
Cataclasite
“Shattered by seismic force”
Tactite
“Contact metamorphism's colorful creation”
Slate (Purple)
“A regal twist on a classic rock”
Mariposite
“Gold country's green companion”
Fenite
“Altered by alkaline magma”
Fulgurite
“Lightning frozen in stone”
Anthracite
“Coal perfected by pressure”
Jade (Nephrite)
“The ancient stone of kings”
Lapis Lazuli
“The original ultramarine blue”
Chlorite Schist
“Soft, green, and foliated”
Granofels
“High-grade without the foliation”
Metaquartzite
“Sandstone reborn as solid quartz”
Garnet Mica Schist
“Glittering garnets in a mica matrix”
Pseudotachylyte
“Glass forged by earthquake friction”
Hornblende Gneiss
“Banded beauty from the deep crust”
Unakite
“Pink and green from altered granite”
Jadeite
“The rarer, harder jade”
Calc-silicate Hornfels
“Baked limestone transformed”
Eclogite (Garnet-Omphacite)
“The densest rock at Earth's surface”
Talc Schist
“The softest metamorphic rock”
Spotted Slate
“Metamorphism caught in the act”
Staurolite Schist
“Fairy crosses in foliated rock”
Buchite
“Sediment fused to glass by lava”
Sillimanite Gneiss
“Evidence of extreme crustal heat”
Cordierite Hornfels
“Baked to hardness by magma's heat”
Jade (Omphacite Jade)
“The mysterious third jade”
Kyanite Schist
“Blue blades in a foliated matrix”
Gondite
“Manganese-rich metamorphic rarity”
Tremolite Schist
“White amphibole in a foliated frame”
Tanzanite Zoisite (Anyolite)
“Ruby and zoisite fused together”
Pelite
“Metamorphosed mud with a mineral story to tell”
Phengite Schist
“High-pressure mica from subduction zones”
Rodingite
“Calcium-enriched by serpentinizing fluids”
Glaucophane Schist
“Blue amphibole from the subduction zone”
Mineral
Quartz
“Earth's most versatile crystal”
Pyrite
“Fool's gold with real value”
Turquoise
“The sky stone”
Fluorite
“The most colorful mineral”
Malachite
“Swirls of copper green”
Galena
“Lead's shining ore”
Labradorite
“The aurora in a stone”
Hematite
“The red planet's pigment”
Alexandrite
“Emerald by day, ruby by night”
Magnetite
“Earth's natural magnet”
Topaz
“Harder than steel”
Opal
“Fire in a stone”
Garnet
“The metamorphic gemstone family”
Calcite
“The backbone of limestone”
Azurite
“Deep blue copper treasure”
Rhodonite
“Rose-pink manganese beauty”
Apatite
“The mineral in your bones”
Chalcopyrite
“The golden ore of copper”
Celestine
“Sky-blue strontium crystal”
Cassiterite
“The tin mineral that launched the Bronze Age”
Sphalerite
“Zinc's dazzling disguise”
Cinnabar
“Brilliant red, deadly mercury”
Tourmaline
“The rainbow mineral”
Barite
“The heavyweight mineral”
Wollastonite
“The eco-friendly industrial mineral”
Olivine
“Earth's most abundant upper mantle mineral”
Muscovite
“The transparent mica”
Biotite
“The dark mica that's everywhere”
Beryl
“One mineral, many gemstones”
Rutile
“The titanium mineral with needle-like beauty”
Zircon
“Earth's oldest surviving crystal”
Feldspar (Orthoclase)
“The most common mineral you've never noticed”
Corundum
“Rubies and sapphires in one mineral”
Spinel
“The gem mistaken for ruby”
Tanzanite (Zoisite)
“Discovered in 1967, found nowhere else”
Epidote
“Pistachio green crystals”
Chrysocolla
“Turquoise's copper cousin”
Borax
“The mineral that built a desert empire”
Sodalite
“Royal blue without the royal price”
Molybdenite
“Slippery silver sheets of molybdenum”
Wolframite
“The heavyweight tungsten ore”
Powellite
“Fluorescent calcium molybdate”
Scheelite
“Tungsten ore that glows blue”
Smithsonite
“The zinc carbonate chameleon”
Prehnite
“Translucent green grape clusters”
Arsenopyrite
“Fool's gold's toxic twin”
Variscite
“The turquoise lookalike”
Crocoite
“Brilliant orange lead chromate”
Dioptase
“Emerald-green copper crystals”
Adamite
“Neon yellow-green zinc crystals”
Cuprite
“Deep red crystals of copper oxide”
Wulfenite
“Paper-thin orange crystal plates”
Hemimorphite
“Two-faced zinc silicate”
Vivianite
“Colorless when fresh, deep blue in light”
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