Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Semiblack Opal
Opal with a dark grey body tone sitting between black and light opal, giving play-of-color rich contrast at an accessible price.
gemstone
Yellow Opal
A cheerful yellow opal ranging from translucent common opal to golden fire opal, colored by trace iron in the silica.
gemstone
Pineapple Opal
A rare opal pseudomorph from White Cliffs, Australia, formed as opal replaced clustered crystals into a pineapple-like shape.
gemstoneHoney Opal
A warm golden-to-amber opal ranging from translucent common opal to precious stones that flash play-of-color over a honey body.
gemstone
Black Opal
The rarest and most valuable opal, with a dark body tone that makes its flashing rainbow play-of-color blaze brilliantly.
gemstonePeach Opal
A gentle peach-to-apricot opal, mostly common opal colored by trace iron, prized for its soft warm pastel body.
gemstone
Emerald in Matrix
Natural emerald crystals still embedded in their host rock, prized as mineral specimens that show how the gem grew in place.
gemstone
Quilpie Opal
Boulder opal from the Quilpie district of Queensland, Australia, with bright color set in dark ironstone matrix.
gemstone
Wood Opal
Fossil wood replaced by opaline silica that preserves wood grain, occasionally showing the play-of-color of precious opal.
gemstoneMintabie Opal
Precious opal from the Mintabie field in South Australia, known for hard, bright crystal opal and some dark-bodied stones.
gemstone
Peacock Opal
A precious opal showing dominant peacock-like blue, green and teal play-of-color, often on Ethiopian material.
gemstone
Oregon Opal
Opal from Oregon, USA, ranging from translucent blue Owyhee opal to clear and fiery contra-luz precious opal from Opal Butte.
gemstone
Chocolate Opal
Precious opal with a warm chocolate-brown body tone that makes its rainbow play-of-color glow, mainly from Ethiopia and Mexico.
gemstone
Opalized Wood
Fossilized wood in which the original organic structure has been replaced by opal, sometimes showing precious play-of-color.
gemstone
Coober Pedy Opal
Australia's classic light-bodied precious opal from Coober Pedy, famed for milky white stones flashing pastel rainbow play-of-color.
gemstoneContra-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.
gemstoneWhite Cliffs Opal
Precious opal from the historic White Cliffs field in New South Wales, Australia, famous for light opal and rare opal pineapples.
gemstone
Virgin Valley Opal
Nevada's famous precious opal, including vivid black opal and opalized wood, renowned for brilliance but a notable tendency to craze.
gemstone
Lightning Ridge Opal
Opal from Lightning Ridge, Australia, the world's premier source of black opal with brilliant color on a dark body.
gemstone
Yowah Nut Opal
Small ironstone concretions from Yowah, Queensland, whose hollow or veined centers hold brilliant precious boulder opal.
gemstone
Aquamarine Matrix
Aquamarine crystals still attached to their natural host rock, prized as mineral specimens showing beryl in its original pocket setting.
mineralIce Opal
A clear, glassy, near-colorless opal resembling ice, sometimes with subtle internal flashes 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
Opalite
A man-made opalescent glass that glows milky blue in reflected light and warm orange when backlit, often sold as a crystal.
crystal