Rock & Mineral Encyclopedia
Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.
Pearl
An organic gem formed inside mollusks from layered nacre, prized for its iridescent luster and classic elegance.
gemstonePipestone
A soft, fine-grained red metamorphosed claystone, sacred to many Native American peoples and carved into ceremonial pipes.
metamorphicPolyhedroid Agate
A rare agate that forms naturally with flat polygonal faces and angular geometric shapes rather than the usual rounded nodule.
gemstone
Pineapple Opal
A rare opal pseudomorph from White Cliffs, Australia, formed as opal replaced clustered crystals into a pineapple-like shape.
gemstone
Fossil Opal
Fossil material whose original substance has been replaced by opal, preserving ancient shapes in common or play-of-color opal.
gemstone
Scepter Quartz
Quartz with a wider crystal 'cap' that grew over a narrower stem, forming a natural scepter or mushroom shape.
crystal
Maskelynite
A natural glass formed when plagioclase feldspar is transformed by shock pressure during meteorite impacts, preserving crystal shape but losing crystal structure.
mineral