Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Calaverite
A brass- to silver-yellow gold telluride that is a major gold ore, famous from Cripple Creek and Kalgoorlie.
mineral
Jade
A tough, prized ornamental gem that is actually two distinct minerals, jadeite and nephrite, revered for millennia in many cultures.
gemstone
Peach Opal
A gentle peach-to-apricot opal, mostly common opal colored by trace iron, prized for its soft warm pastel body.
gemstone
Syrian Garnet
Syrian Garnet is an old trade name for fine deep-red almandine, historically tied to the Syriam region and prized as 'precious garnet.'
gemstone
Carnotite
A bright yellow, radioactive potassium uranyl vanadate that is a major ore of both uranium and vanadium.
mineral
Kimberlite
A rare ultramafic volcanic rock that erupts from deep in the mantle and is the primary natural source of diamonds.
igneous
Chalcopyrite
A brassy copper-iron sulfide that is the world's most important copper ore, often showing colorful iridescent tarnish.
mineral
Limonite
Limonite is an amorphous brown iron oxide ore, the rust-colored material behind ochre pigments and bog iron.
mineral
Golden Emerald
A trade name occasionally used for golden-yellow beryl (golden beryl or heliodor), the iron-colored yellow variety of the emerald mineral.
gemstone
Fossil Opal
Fossil material whose original substance has been replaced by opal, preserving ancient shapes in common or play-of-color opal.
gemstone
Golden Feldspar
A trade name for golden-yellow gem feldspars, including golden orthoclase, golden sunstone, and golden labradorite.
gemstone
Shell Opal
Fossil shells whose original material has been replaced by opal, preserving ancient marine forms in common or precious opal.
gemstone
Opal
A hydrated silica gemstone famous for its shimmering play-of-color, ranging from white and black opal to fiery orange fire opal.
gemstone
Crystal Opal
Precious opal with a transparent or translucent body, letting play-of-color glow with exceptional depth and clarity.
gemstone
Montana Moss Agate
A translucent chalcedony from Montana filled with black and red dendritic inclusions that look like moss, ferns, or scenic landscapes.
gemstone
Contra-Luz Opal
A rare opal whose play-of-color appears only when light passes through it, glowing best when backlit or held to the light.
gemstone
Mustard Tourmaline
A warm mustard to brownish-yellow tourmaline, colored by iron or manganese, sitting between yellow and brown dravite tones.
gemstone
Golden Healer Quartz
Quartz colored or coated by golden iron oxides such as limonite or goethite, giving a warm sunlit yellow glow.
crystal
Danburite
A glassy calcium borosilicate forming wedge-tipped prismatic crystals, usually colorless to pale yellow or pink, sometimes faceted as a gem.
crystal
Fire Opal
A translucent to transparent opal in warm yellow, orange, and red tones, prized for body color rather than play-of-color.
gemstone
Millerite
A nickel sulfide famous for delicate brass-yellow hairlike crystals that form radiating sprays inside cavities and geodes.
mineral
Smithsonite
Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.
mineral
Pyromorphite
A lead phosphate secondary mineral known for barrel-shaped green to yellow crystals formed in oxidized lead deposits.
mineral
Ocean Jasper
A multicolored orbicular chalcedony from Madagascar famous for its circular eye-like orbs in greens, pinks, whites, and yellows.
sedimentary