Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Neon Blue Tourmaline
An intensely glowing copper-bearing tourmaline whose electric neon-blue color makes it one of the most valuable gems in the world.
gemstone
Neon Green Tourmaline
An intensely glowing green tourmaline, often copper-bearing, whose electric, almost luminous color recalls paraiba tourmaline.
gemstone
Purple-Pink Tourmaline
Elbaite tourmaline in purplish-pink to magenta hues, colored by manganese, prized for its vivid orchid-like tones.
gemstone
Bi-Color Tourmaline
Tourmaline displaying two distinct colors in a single crystal, a natural color-zoning effect that makes each stone unique.
gemstone
Cat's Eye Green Tourmaline
Green tourmaline cut as a cabochon to show a sharp moving band of light (chatoyancy) caused by fine parallel inclusions.
gemstone
Cat's Eye Pink Tourmaline
Pink tourmaline cut en cabochon to reveal a moving band of light, a phenomenal gem colored by manganese with parallel inclusions.
gemstone
Graphic Feldspar
A pegmatite rock of feldspar intergrown with wedge-shaped quartz that resembles ancient runic or Hebrew writing.
igneous
Povondraite
A rare ferric-iron-dominant tourmaline that forms in oxidized evaporite settings, appearing as black to red-brown prismatic crystals.
mineral
Rossmanite
A rare lithium-aluminum tourmaline with a vacant X site, typically pale pink to colorless and found in lithium pegmatites.
mineral
Buergerite
A rare iron-rich (ferric) species of the tourmaline group, dark brown to bronze-black, named after crystallographer Martin Buerger.
mineral
Feruvite
A calcium- and ferrous-iron-rich tourmaline, the iron analogue of uvite, forming dark brown to black crystals in skarns and metamorphic rocks.
mineral
Foitite
A rare alkali-deficient tourmaline whose X crystal site is largely vacant, giving slender dark blue to bluish-black crystals.
mineral
Dravite
The magnesium-rich brown member of the tourmaline group, named for Austria's Drava River and prized for warm earthy tones.
mineral
Olenite
A rare aluminum-rich species of the tourmaline group, usually colorless to pale, named for the Olenii Range in Russia's Kola Peninsula.
mineral
Elbaite
The lithium-rich tourmaline species responsible for nearly all gem tourmaline, occurring in every color of the rainbow.
mineral
Epidosite
A hard, pistachio-green rock composed mainly of epidote and quartz, formed by hydrothermal alteration of mafic rocks.
metamorphicMidnight Obsidian
A trade name for deep, solid black obsidian, natural volcanic glass prized for its uniform jet-black color and glassy luster.
igneous
Chrome-Dravite
A chromium-dominant tourmaline related to dravite, producing intensely deep green to blackish-green crystals from chromium-rich metamorphic rocks.
mineral
Biotite Schist
A foliated metamorphic rock dominated by glittering dark biotite mica, formed from mudstones under medium-grade regional metamorphism.
metamorphic
Liddicoatite
A rare calcium-rich lithium tourmaline famous for the spectacular concentric color zoning seen in polished cross-section slices.
mineral
Red Jasper
An opaque, iron-rich variety of microcrystalline quartz known for its deep brick-red color and ancient history as a stone of strength and grounding.
gemstone
Dalmatian Jasper
A cream-colored spotted stone resembling a Dalmatian dog, made of feldspar and quartz dotted with dark mineral grains.
igneous
Melanite Garnet
The titanium-rich black variety of andradite garnet, with a brilliant resinous luster prized for mourning and statement jewelry.
gemstone
Zebra Jasper
A black-and-white striped chalcedony-quartz rock whose bold zebra-like banding makes it a popular ornamental and lapidary stone.
sedimentary