What's That Rock?📚 Free stone guide
Stones: the free identification guide
How to identify more than 100 rocks, minerals and gemstones, tell the real from the fake, and what they are typically worth. Pick a stone, or search the list.
100 stones
- AgateMineralBanded, fine-grained quartz (chalcedony).
- AmazoniteGemstoneA blue-green variety of microcline feldspar, often with fine white streaks or a grid-like pattern.
- AmberGemstoneFossil tree resin millions of years old.
- AmethystGemstoneThe purple variety of quartz.
- AmmoniteFossilThe coiled shell of an extinct sea animal related to squid and octopus.
- AndesiteRockA gray, fine-grained volcanic rock named for the Andes.
- ApatiteMineralA phosphate mineral that is the number 5 on the Mohs hardness scale.
- AquamarineGemstoneThe pale blue to blue-green variety of beryl.
- AragoniteMineralA calcium carbonate with the same chemistry as calcite but a different structure.
- AventurineGemstoneQuartz filled with tiny flakes of mica that make it glitter.
- AzuriteMineralA deep blue copper mineral.
- BariteMineralA very heavy white or pale blue mineral made of barium sulfate.
- BasaltRockA dark, fine-grained volcanic rock that forms from cooled lava.
- BiotiteMineralA black or dark brown mica that peels into thin, shiny, flexible sheets.
- BloodstoneGemstoneDark green chalcedony with bright red spots of iron oxide, like drops of blood.
- BorniteMineralA copper ore nicknamed peacock ore for its blue, purple and bronze iridescent tarnish.
- BrecciaRockA rock made of sharp-edged fragments cemented together.
- CalciteMineralA very common calcium carbonate mineral.
- CarnelianGemstoneOrange to red-brown chalcedony colored by iron oxide.
- CelestineMineralA delicate pale blue mineral made of strontium sulfate.
- ChalcopyriteMineralAn important copper ore.
- ChertRockA hard, fine-grained rock made of microscopic quartz.
- ChrysocollaMineralA soft blue-green copper mineral often found with malachite and azurite.
- CinnabarMineralA bright red mineral that is the main ore of mercury.
- CitrineGemstoneYellow to orange-brown quartz.
- CoalRockA black, burnable sedimentary rock made from ancient plant remains.
- ConglomerateRockA sedimentary rock made of rounded pebbles and gravel cemented together.
- DiamondGemstonePure carbon with a crystal structure that makes it the hardest natural material.
- DolomiteMineralA calcium magnesium carbonate that looks like calcite but fizzes only slowly.
- EmeraldGemstoneThe green variety of beryl, colored by chromium and sometimes vanadium.
- EpidoteMineralA pistachio-green mineral common in metamorphic rocks.
- FeldsparMineralThe most common group of minerals in the Earth's crust.
- FluoriteMineralA colorful calcium fluoride mineral that forms cubes and octahedra.
- Fossil coralFossilThe stony skeleton of ancient coral colonies.
- GalenaMineralThe main ore of lead.
- GarnetGemstoneA group of related minerals, most often deep red.
- GneissRockA banded metamorphic rock with alternating light and dark layers.
- GoethiteMineralA common rusty-brown iron oxide hydroxide.
- GraniteRockA common light-colored igneous rock with visible grains of quartz, feldspar and mica.
- HaliteMineralRock salt, the mineral form of table salt.
- HematiteMineralAn iron oxide that ranges from shiny gray metal-like crystals to dull red earth.
- HornblendeMineralA dark green to black mineral common in granite and metamorphic rocks.
- Iron meteoriteMeteoriteA piece of metal from the core of a broken asteroid, made mostly of iron and nickel.
- JadeGemstoneTwo different tough minerals are called jade: nephrite and jadeite.
- JasperRockOpaque fine-grained quartz colored by iron and other impurities.
- JetGemstoneA glossy black gemstone made of compressed fossil wood.
- KunziteGemstoneThe pink to lilac gem variety of spodumene.
- KyaniteMineralA blue blade-shaped mineral with a strange feature: it is hard in one direction and soft in another.
- LabradoriteMineralA feldspar that flashes blue, green or gold as it is tilted.
- Lapis lazuliRockA deep blue rock made mostly of lazurite, with white calcite patches and golden pyrite flecks.
- LimestoneRockA sedimentary rock made mostly of calcite, often from shells and sea life.
- MagnetiteMineralA black iron oxide that is strongly attracted to a magnet.
- MalachiteMineralA bright green copper mineral, often with curved bands and rings.
- MarbleRockLimestone that has been changed by heat and pressure into a tight mass of interlocking calcite crystals.
- MoldaviteOtherA bottle-green natural glass formed when a large meteorite hit Earth about 15 million years ago, in what is now…
- MoonstoneGemstoneA feldspar with a floating, milky blue or white glow that moves as the stone is turned.
- MorganiteGemstoneThe pale pink to peach variety of beryl, the same mineral as emerald and aquamarine.
- Muscovite micaMineralA shiny, silvery mineral that peels into thin, flexible, see-through sheets.
- ObsidianRockNatural volcanic glass formed when lava cools very quickly.
- OnyxGemstoneChalcedony with straight, parallel black and white bands.
- OpalMineralA form of silica that holds water and has no crystals.
- PeridotGemstoneThe gem form of olivine, always green.
- Petrified woodFossilWood turned to stone.
- PumiceRockA frothy volcanic rock filled with gas bubbles.
- PyriteMineralIron sulfide with a brassy yellow, metallic look, known as fool's gold.
- QuartzMineralOne of the most common minerals in the Earth's crust.
- QuartziteRockA hard metamorphic rock formed when sandstone is changed by heat and pressure.
- RealgarMineralA bright orange-red arsenic mineral.
- RhodochrositeMineralA pink to raspberry-red manganese carbonate.
- RhodoniteMineralA pink to rose manganese silicate, usually threaded with black manganese oxide veins.
- RhyoliteRockA light-colored volcanic rock with the same chemistry as granite but very fine grains, because it cooled quickly.
- Rose quartzMineralPale pink quartz that is usually cloudy or translucent.
- RubyGemstoneThe red variety of corundum, colored by chromium.
- SandstoneRockA sedimentary rock made of cemented sand grains.
- SapphireGemstoneCorundum in any color except red.
- SchistRockA metamorphic rock full of flat, shiny mineral flakes (usually mica) that give it a glittery, wavy look.
- ScoriaRockA dark red, brown or black volcanic rock full of gas bubbles.
- SeleniteMineralA clear, colorless variety of gypsum that forms flat sheets and long blades.
- SerpentineMineralA group of green to yellow-green minerals with a slick, waxy look.
- ShaleRockA soft sedimentary rock made of compacted mud and clay.
- Shark toothFossilA fossil tooth from a shark that lived millions of years ago.
- SideriteMineralAn iron carbonate that is tan to brown and often forms rounded crystals or nodules.
- SlateRockA fine-grained metamorphic rock that splits into smooth flat sheets.
- Smoky quartzMineralBrown to nearly black quartz.
- SodaliteMineralA deep blue mineral, often crossed by white veins.
- SphaleriteMineralThe main ore of zinc.
- SpinelGemstoneA hard, clear gem found in red, pink, blue and other colors.
- StauroliteMineralA brown mineral that often grows in cross shapes, called fairy crosses.
- StibniteMineralThe main ore of antimony.
- Stony meteoriteMeteoriteThe most common kind of meteorite.
- SunstoneGemstoneA feldspar that sparkles with tiny metallic flakes, giving an orange-gold glitter inside the stone.
- TalcMineralThe softest mineral on the Mohs scale.
- TanzaniteGemstoneA blue-violet variety of zoisite found only near Mount Kilimanjaro in Tanzania.
- Tiger's eyeGemstoneGolden-brown quartz with a silky band of light that moves when the stone is turned (chatoyancy).
- TopazGemstoneA hard aluminum silicate gem found in many colors.
- TourmalineGemstoneA group of boron silicate minerals found in nearly every color.
- TravertineRockA banded, often pitted limestone deposited by hot or cool springs.
- TrilobiteFossilAn extinct sea creature with a three-lobed body, an arthropod, a distant relative of crabs and insects.
- TurquoiseGemstoneA blue-to-green copper and aluminum phosphate.
- ZirconGemstoneA heavy, brilliant gemstone and the oldest mineral found on Earth.
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