Rock & Mineral Encyclopedia

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

Aventurine

A translucent quartz speckled with glittery mineral inclusions that produce a shimmering aventurescence, most often green.

A naturally blue quartz colored by tiny mineral inclusions such as dumortierite or scattered rutile and tourmaline fibers.

A soft, soothing powder-blue variety of calcite, a common calcium carbonate mineral often sold as gentle tumbled stones.

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

A soft mint-to-apple-green variety of calcite, a common calcium carbonate mineral popular as soothing tumbled stones.

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

A deep blue copper carbonate mineral that forms in oxidized copper deposits, often alongside green malachite.

Smithsonite is a zinc carbonate ore famous for glassy botryoidal crusts in blue-green, pink, and yellow hues.

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

A vivid turquoise-blue glass sold as obsidian; this bright color is virtually always manufactured rather than natural volcanic glass.

A deep teal glass sold as obsidian; the saturated blue-green color is manufactured and not found in natural volcanic glass.