Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Pegmatite
An exceptionally coarse-grained igneous rock, often granitic, famous for hosting large crystals and many gemstones.
igneous
Ruby
The red, chromium-colored variety of corundum, prized as one of the most valuable colored gemstones and second only to diamond in hardness.
gemstone
Orange Calcite
A soft, glowing orange variety of calcite colored by iron oxides, popular as tumbled stones and known for fizzing in acid.
mineralPeruvian Blue Opal
A translucent common opal from the Andes prized for its serene blue to blue-green color, usually cut into cabochons and beads.
gemstone
Lamprophyre
A dark, mineral-rich dike rock with abundant mica or amphibole phenocrysts set in a fine groundmass, often associated with gold and diamonds.
igneous
Limburgite
A dark, glass-rich volcanic rock of olivine and augite phenocrysts set in a feldspar-free glassy groundmass, named from the Kaiserstuhl region.
igneous
Yellow Garnet
A trade term for yellow garnets, including golden grossular, yellow andradite (topazolite), and yellow-green Mali garnet.
gemstone
Micrite
A very fine-grained limestone made of microcrystalline calcite mud, dense and smooth, deposited in calm carbonate settings.
sedimentary
Serpentine
A group of green magnesium silicate minerals with a smooth, waxy feel, often carved and sometimes sold as imitation jade.
mineralGrandite Garnet
Grandite is an intermediate garnet between grossular and andradite, common in skarns and prized for vivid green to golden crystals.
mineral
Alexandrite
A rare color-change chrysoberyl that appears green in daylight and red under incandescent light, sometimes called emerald by day, ruby by night.
gemstoneWillow Creek Jasper
A prized Idaho jasper known for porcelain-smooth pastel pinks, creams, and greens in soft swirling, orbicular patterns.
mineral
Paraiba Tourmaline
An intensely glowing copper-bearing tourmaline famed for its electric neon blue-green color and extreme rarity and value.
gemstone
Tinguaite
A fine-grained green phonolitic dike rock rich in nepheline and aegirine, the hypabyssal equivalent of phonolite.
igneousCarrasite Jasper
An orbicular Madagascar jasper related to ocean jasper, showing eyes and swirls in cream, green, and earthy tones.
mineral
Smithsonite
Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.
mineralExotica Jasper
Also called Sci-Fi Jasper, a Mexican jasper-rhyolite with swirling abstract patterns in cream, tan, gray, pink, and green.
gemstoneMadagascar Opal
Opal from Madagascar spanning colorful common opal and some precious opal, including pink, green and boulder-type material.
gemstone
Uvite
A calcium-magnesium tourmaline that forms in metamorphosed limestones, typically dark green to brown and often in well-formed crystals.
mineral
Gahnite
A hard zinc-rich member of the spinel group, usually dark blue-green to black, forming octahedral crystals in metamorphic and pegmatitic rocks.
mineral
Ocean Jasper
A multicolored orbicular chalcedony from Madagascar famous for its circular eye-like orbs in greens, pinks, whites, and yellows.
sedimentaryMulticolor Tourmaline
Tourmaline crystals displaying two or more distinct colors at once, including the famous pink-and-green watermelon variety.
gemstone