Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Cinnamon Stone
The warm cinnamon-to-honey-brown variety of grossular garnet, also known as hessonite, with a characteristic swirly internal texture.
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
Melanite Garnet
The titanium-rich black variety of andradite garnet, with a brilliant resinous luster prized for mourning and statement jewelry.
gemstone
Amegreen
A natural bicolor quartz blending amethyst purple with prasiolite green in a single crystal, prized as a metaphysical heart-crown stone.
crystal
Bixbyite
A black metallic manganese iron oxide famous for sharp cubic crystals, classically found with red beryl and topaz in Utah rhyolite.
mineral
Aventurine Feldspar
A feldspar, better known as sunstone, that sparkles with metallic glints from tiny mineral platelets, an effect called aventurescence.
gemstone
Woodbine Jasper
An earthy-toned jasper with vine-like or scenic patterning, valued by lapidaries for warm browns, reds, and creams that polish to a smooth finish.
gemstone
Septarian Concretion
A rounded sedimentary nodule cracked internally and filled with veins of yellow calcite, prized for its striking dragon-skin patterning.
sedimentary
Montana Moss Agate
A translucent chalcedony from Montana filled with black and red dendritic inclusions that look like moss, ferns, or scenic landscapes.
gemstone
Forest Green Tourmaline
A deep, rich forest-green elbaite tourmaline (verdelite) colored mainly by iron, with strong pleochroism and excellent durability.
gemstone
Anatase
A tetragonal titanium dioxide polymorph forming steep bipyramidal crystals, often deep blue to black with brilliant adamantine luster.
mineral
Andalusite
A pleochroic aluminum silicate that flashes green and reddish-brown from different angles, with a cross-marked variety called chiastolite.
mineral
Essexite
A dark, silica-undersaturated gabbroic rock containing nepheline along with plagioclase, alkali feldspar, and pyroxene, also known as nepheline monzogabbro.
igneous
Velvet Opal
Opal with a soft, velvety surface sheen rather than sharp play-of-color, prized for its gentle glow.
gemstone
Lepidolite
A soft lithium-bearing mica with a lilac to purple color and pearly, flaky sheen, an important ore of lithium.
mineral
Diabase
A tough, dark, medium-grained igneous rock with the composition of basalt, common in dikes and sills.
igneous
Achroite
The rare colorless variety of tourmaline, named from the Greek for 'without color' and prized by collectors.
gemstone
Sparite
Coarse, clear-to-white crystalline calcite that cements limestones, contrasting with fine muddy micrite.
sedimentary
Syenite
A coarse-grained intrusive igneous rock dominated by alkali feldspar with little or no quartz.
igneous
Red Opal
An opal with a deep red body color, often a variety of Mexican fire opal, prized for its warm, glowing intensity.
gemstone
Maxixe
A deep blue beryl with a color caused by radiation that fades in light, named after the Maxixe mine in Brazil.
gemstone
Brown Tourmaline
Warm brown tourmaline, usually magnesium-rich dravite, with tones from pale champagne to deep coffee-brown.
gemstone
Snake Skin Agate
A chalcedony with a distinctive scaly, reptile-skin surface texture, typically in pale tan, pink, and gray tones.
gemstone
Leopard Opal
A patterned common opal with mottled, leopard-like spots and blotches, prized as an ornamental and cabochon stone.
gemstone