Rock & Mineral Encyclopedia

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

Smoky Quartz

The smoky brown to gray variety of quartz, colored by natural irradiation, valued as both a gemstone and crystal specimen.

An old name for a dull leek-green variety of quartz or chalcedony colored by green mineral inclusions, historically called mother of emerald.

Black volcanic glass dotted with small light-colored mineral specks resembling stars scattered across a night sky.

A foliated metamorphic rock of calcite mixed with mica, quartz, and calc-silicate minerals, derived from marly sediments.

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

Clear quartz filled with mineral inclusions that look like underwater gardens, mossy landscapes, or floating scenery.

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