Rock & Mineral Encyclopedia

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

Particolored Tourmaline

A tourmaline displaying two or more distinct colors in a single crystal, prized for natural color zoning like watermelon and bicolor stones.

Fossilized tree resin, warm and lightweight, sometimes preserving ancient insects and plant matter inside.

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

An opaque blue variety of chalcedony jasper, less common than red or green forms, colored by mineral inclusions.

A banded agate that diffracts transmitted light into rainbow colors when cut thin and backlit, producing a spectacular iridescence.

Australia's classic light-bodied precious opal from Coober Pedy, famed for milky white stones flashing pastel rainbow play-of-color.