Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Zebra Jasper
A black-and-white striped chalcedony-quartz rock whose bold zebra-like banding makes it a popular ornamental and lapidary stone.
sedimentary
Matrix Opal
Opal in which precious play-of-color is intimately dispersed through the pores of its host rock rather than forming a solid seam.
gemstone
Tactite
A contact-metasomatic calc-silicate rock, essentially a skarn, formed where intrusions react with carbonate rocks and often host ore.
metamorphic
Scoria
A dark, highly vesicular volcanic rock full of gas bubbles, denser than pumice, common as red or black lava rock.
igneousLuxullianite
A distinctive tourmaline-rich granite from Cornwall, prized as an ornamental stone for its pink feldspar set with radiating black tourmaline.
igneous
Norite
A coarse-grained mafic plutonic rock similar to gabbro but with orthopyroxene as the dominant pyroxene instead of clinopyroxene.
igneous
Shungite
A rare black carbon-rich rock from Russia, noted for containing fullerenes and ranging from dull mineralized stone to lustrous noble shungite.
sedimentary
Black Garnet
An opaque black garnet — typically titanium-bearing melanite andradite — historically cut for mourning and Victorian jewelry.
gemstone
Pegmatite
An exceptionally coarse-grained igneous rock, often granitic, famous for hosting large crystals and many gemstones.
igneous
Dalmatian Stone
A cream-colored feldspar-and-quartz rock peppered with dark spots, named for its resemblance to a Dalmatian dog.
igneous
Larvikite
A Norwegian intrusive rock whose feldspar crystals flash silvery-blue, widely used as blue pearl granite countertops.
igneous
Bituminous Shale
A dark, organic-rich shale loaded with kerogen and bitumen that can yield oil and gas, often finely laminated and combustible.
sedimentaryBlack Onyx
A solid jet-black chalcedony, usually a dyed and treated agate, prized for sleek polished beads, cabochons, and intaglios.
gemstone
Teal Tourmaline
A sought-after elbaite tourmaline in teal hues that blend blue and green, prized for its ocean-like color.
gemstone
Rose Tourmaline
A soft to medium pink elbaite tourmaline in rose hues, colored by manganese and prized for romantic jewelry.
gemstone
Red Tourmaline
Vivid red to raspberry tourmaline, the most intense colors are marketed as rubellite, colored by manganese in the elbaite structure.
gemstone
Biotite Schist
A foliated metamorphic rock dominated by glittering dark biotite mica, formed from mudstones under medium-grade regional metamorphism.
metamorphic
Blue Tourmaline
Tourmaline in blue tones, encompassing iron-colored indicolite and the rare neon copper-bearing Paraiba, among the scarcer tourmaline colors.
gemstone
Lemon Tourmaline
A bright lemon-to-canary yellow tourmaline colored by manganese, among the more cheerful and uncommon hues in the tourmaline family.
gemstone
Orange Tourmaline
A warm orange to tangerine tourmaline, an uncommon hue produced by manganese and iron in the crystal.
gemstone
Violet Tourmaline
Elbaite tourmaline in violet to purple hues colored by manganese, a relatively scarce and sought-after tourmaline color.
gemstone
Anthracite
The highest-rank coal, a hard, lustrous black rock that burns cleanly with little smoke and high heat output.
metamorphic
Paraiba Tourmaline
An intensely glowing copper-bearing tourmaline famed for its electric neon blue-green color and extreme rarity and value.
gemstone
Chrome Tourmaline
An intensely green tourmaline colored by chromium and vanadium, prized for its vivid emerald-like color from East Africa.
gemstone