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.

Iron-stained sandstone whose red color comes from hematite coatings, formed in oxidizing desert, river, and coastal environments.

A man-made glittering glass colored deep blue with cobalt and studded with tiny copper crystals that mimic a starry night sky.

A landscape-patterned Chinese jasper prized for warm cherry-red, cream, and green bands resembling painted scenery.

A man-made glittering glass packed with tiny copper crystals, traditionally reddish-brown but also made in blue and green.

A porous sedimentary rock naturally saturated with bitumen, dark, tarry-smelling, and historically mined for paving.

A coarse sedimentary rock of rounded pebbles and gravel cemented in a finer matrix, recording ancient rivers and beaches.

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