Rock & Mineral Encyclopedia

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

Dumortierite Quartz

Quartz colored blue by inclusions of the mineral dumortierite, giving a denim-like blue ornamental stone harder than dumortierite alone.

A green ornamental stone, often serpentine-rich marble or verde antique, valued for its rich green color and white veining.

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

A red-toned banded chalcedony colored by iron oxides, ranging from natural carnelian-like reds to heat-treated stones.

A warm golden-to-amber opal ranging from translucent common opal to precious stones that flash play-of-color over a honey body.

A golden-toned opal ranging from translucent common opal to precious stones flashing color against a warm yellow body.

A glowing orange-to-red opal whose warm body color resembles flame; some stones add flashes of play-of-color.

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

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

Small, smooth, teardrop-shaped beads of basaltic volcanic glass formed from airborne lava droplets, often paired with Pele's hair.

An organic gem formed inside mollusks from layered nacre, prized for its iridescent luster and classic elegance.