Rock & Mineral Encyclopedia

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

Sandstone

A clastic sedimentary rock made of cemented sand grains, often quartz, recording ancient beaches, deserts, and rivers.

A quartz crystal containing pink to lilac lithium-bearing mineral inclusions that give a soft cloudy lavender or rose coloration.

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

The lowest rank of coal, a soft brown carbon-rich rock formed from compacted peat, used mainly for electricity generation.

Limestone built from tiny rounded ooid grains resembling fish roe, formed in warm, agitated shallow seas.

A soft pink common opal from the Peruvian Andes, prized for its opaque rosy color rather than play-of-color.

A limestone made of tiny spherical ooids, resembling fish roe, formed in warm, agitated shallow seas.

A jasper whose radiating mineral clusters form flower-like rosettes scattered across an earthy background.