Rock & Mineral Encyclopedia

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

Opalite

A man-made opalescent glass that glows milky blue in reflected light and warm orange when backlit, often sold as a crystal.

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

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

A rare zinc oxide best known for its deep red to orange color, classically from Franklin, New Jersey, and as colorful man-made crystals.

The most common type of mantle peridotite, made of olivine with both orthopyroxene and clinopyroxene, representing fertile upper-mantle rock.

A metamorphic rock made chiefly of manganese-rich spessartine garnet and quartz, formed from ancient manganese-bearing sediments.

An ultramafic intrusive rock made almost entirely of olivine, representing mantle material.