Rock & Mineral Encyclopedia

Search and identify 1,000+ rocks, minerals, crystals, and gemstones — with properties, formation, colors, hardness, and how to tell them apart.

Dragon Vein Agate

A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.

The most common variety of quartz, milky white from microscopic fluid and gas inclusions, forming massive veins worldwide.

Ancient chemically deposited rock of alternating iron-oxide and silica bands recording Earth's early oxygenation and a major iron ore source.

Small ironstone concretions from Yowah, Queensland, whose hollow or veined centers hold brilliant precious boulder opal.