Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Quartz-mica Schist
A foliated metamorphic rock of interlayered quartz and mica, producing a sparkling, easily split rock from metamorphosed sandy shales.
metamorphic
Indicolite
The blue variety of tourmaline, a relatively rare and prized color ranging from teal and greenish blue to deep indigo.
gemstone
Cherry Opal
A translucent red opal, closely related to Mexican fire opal, glowing with a warm cherry-red body color often free of play-of-color.
gemstone
Red Opal
An opal with a deep red body color, often a variety of Mexican fire opal, prized for its warm, glowing intensity.
gemstone
Chrome Pyrope
A chromium-rich pyrope garnet whose intense blood-red color comes from chromium, often mined from ant hills and kimberlite weathering.
gemstone
Pyrargyrite
A silver antimony sulfosalt known as dark ruby silver, an important silver ore with deep red internal reflections.
mineral
Pyrope Garnet
The magnesium-rich garnet famed for its intense blood-red 'fire,' historically the Bohemian garnet of Victorian jewelry.
gemstone
Bohemian Garnet
Small, intensely red chrome-pyrope garnets from the Czech Bohemian region, famous for densely set antique Victorian jewelry.
gemstone
Spinel
A durable magnesium aluminum oxide gem that occurs in many colors and was long mistaken for ruby.
gemstone
Alexandrite
A rare color-change chrysoberyl that appears green in daylight and red under incandescent light, sometimes called emerald by day, ruby by night.
gemstone
Aventurine
A translucent quartz speckled with glittery mineral inclusions that produce a shimmering aventurescence, most often green.
crystal
Rossmanite
A rare lithium-aluminum tourmaline with a vacant X site, typically pale pink to colorless and found in lithium pegmatites.
mineral
Graphic Feldspar
A pegmatite rock of feldspar intergrown with wedge-shaped quartz that resembles ancient runic or Hebrew writing.
igneous
Chrome-Dravite
A chromium-dominant tourmaline related to dravite, producing intensely deep green to blackish-green crystals from chromium-rich metamorphic rocks.
mineral
Gem Silica
A rare, intensely blue chalcedony colored by copper-rich chrysocolla, prized as the most valuable of the blue chalcedonies.
gemstone
Latite
The fine-grained volcanic equivalent of monzonite, an intermediate lava with nearly equal feldspars and little free quartz.
igneousLuxullianite
A distinctive tourmaline-rich granite from Cornwall, prized as an ornamental stone for its pink feldspar set with radiating black tourmaline.
igneous
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
Elbaite
The lithium-rich tourmaline species responsible for nearly all gem tourmaline, occurring in every color of the rainbow.
mineral
Green Aventurine
A green quartz speckled with shimmering fuchsite mica that produces a glittering aventurescence, popular as an affordable ornamental stone.
mineral
Tiger's Eye
A golden-brown chatoyant quartz with a shimmering silky band of light, formed when quartz replaces fibrous crocidolite.
gemstone
Achroite
The rare colorless variety of tourmaline, named from the Greek for 'without color' and prized by collectors.
gemstone
Metasandstone
Sandstone altered by metamorphism, with partly recrystallized quartz grains, transitional between true sandstone and quartzite.
metamorphicSonoran Sunset Jasper
A vivid copper-bearing Mexican stone of red cuprite and green chrysocolla that evokes a desert sunset.
mineral