Rock & Mineral Encyclopedia

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

Prase

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

An opaque earth-toned jasper colored brown by iron oxides, ranging from pale tan to deep chocolate.

A fiery jasper whose red, orange, and yellow plumes lick across the stone like flames against an earthy background.

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

A soft-toned cream-to-butterscotch jasper colored by iron oxides, prized by lapidaries for its smooth, even, opaque finish.

An opaque green variety of chalcedony quartz colored by iron and chlorite-group inclusions, prized as a durable carving and cabochon stone.

A deep red banded agate colored by iron oxides, valued as a vivid red lapidary and jewelry stone.

A richly colored red banded agate prized by lapidaries for its deep crimson-to-brown tones reminiscent of pigeon's blood.

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

A banded variety of chalcedony quartz, famed for its colorful concentric layers and enormous range of patterns and colors.

The classic agate defined by concentric or parallel bands of chalcedony in varied colors, the archetype of all agate varieties.

A treated chalcedony with a network of crackled veins, usually heated and dyed in vivid colors for affordable, eye-catching beads.

A white to grayish banded chalcedony, the natural base color of much agate and the substrate for many dyed stones.

A banded chalcedony agate with bold alternating dark and light stripes resembling zebra markings, sometimes color-enhanced.

A soft sky-blue chalcedony from the Owyhee region of Oregon and Idaho, prized for its calming, opaque powder-blue color.