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.

A clean, mature sandstone made almost entirely of quartz grains, representing extreme weathering, sorting, and recycling of sediment.

A soft, fine-grained red metamorphosed claystone, sacred to many Native American peoples and carved into ceremonial pipes.