Rock & Mineral Encyclopedia

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

Copper

A soft, reddish native metal with excellent conductivity, mined for wiring, plumbing, and alloys like bronze and brass.

Clear or smoky quartz threaded with golden to reddish needles of rutile, also poetically called Venus hair stone.

A banded chalcedony combining reddish-brown sard with white or black onyx layers, prized since antiquity for carved cameos.

A reddish-brown rare-earth phosphate that is a primary ore of cerium, thorium and other rare-earth elements, often found in placer sands.

A fine-grained clastic rock of silt-sized grains, intermediate between sandstone and mudstone, with a gritty feel.