Rock & Mineral Encyclopedia

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

Molybdenite

Molybdenite is the primary ore of molybdenum, a soft, greasy, silver-gray sulfide that closely resembles graphite.

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 hydrated volcanic glass with pearly, onion-like concentric cracks that pops into lightweight white granules when heated.

Agate that was shattered and naturally re-cemented by silica, creating a mosaic of angular fragments in a quartz matrix.