Rock & Mineral Encyclopedia

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

Cat's Eye Morganite

Pink beryl (morganite) that shows chatoyancy, a moving band of light, when cut as a cabochon, thanks to parallel tube inclusions.

An opal cut to show chatoyancy, a sharp moving band of light like a cat's eye, usually in honey, green or yellow common opal.

The golden-yellow variety of quartz, ranging from pale lemon to deep madeira amber, often produced by heating amethyst.

A conglomerate altered by heat and pressure, often with its rounded pebbles stretched and flattened into elongated lenses.

A soft, talc-rich metamorphic rock with a soapy feel, easily carved and highly heat-resistant for cookware and sculpture.

The highest-rank coal, a hard, lustrous black rock that burns cleanly with little smoke and high heat output.

A vivid greenish-yellow quartz, usually heat-treated or irradiated, prized for its clean clarity and bright lemon color.

A pale green variety of quartz, usually created by heat-treating amethyst, often marketed as green amethyst.

A hard, tough metamorphic rock of fused quartz grains, formed by recrystallizing quartz sandstone under heat and pressure.

A metamorphic rock of calcium-rich silicate minerals formed from impure limestone or dolomite altered by heat and fluids.

A green variety of macrocrystalline quartz, usually the heat- or radiation-altered prasiolite, prized for its soft mint hue.

A tough, fine-grained, non-foliated rock formed by the intense heat of nearby magma baking surrounding rock at contact zones.

A dark, glassy rock formed when frictional heat from fault movement or impact melts rock along narrow veins.

A tough, fine-grained contact-metamorphic rock containing cordierite, often spotted, formed by heat from nearby igneous intrusions.