Rock & Mineral Encyclopedia

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

Amber

Fossilized tree resin, warm and lightweight, sometimes preserving ancient insects and plant matter inside.

A combustible black sedimentary rock formed from ancient plant matter and burned for centuries as a primary fossil fuel.

Calcium-carbonate sedimentary rock packed with visible fossils, recording ancient marine life within an easily scratched, fizzing matrix.

A soft carbonate sedimentary rock made mostly of calcite, often packed with marine fossils and prone to forming caves.