Rock & Mineral Encyclopedia

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

Dragon Vein Agate

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

A hollow rock nodule whose interior cavity is lined with inward-pointing crystals such as quartz, amethyst, or calcite.

A trade name for quartz containing a combination of seven minerals including amethyst, smoky quartz, and cacoxenite, prized by collectors.

Quartz containing a sealed pocket of ancient water, often with a mobile air bubble that moves when the crystal is tilted.

Black volcanic glass that reveals a soft purple-to-violet sheen at certain angles, caused by light interference off aligned inclusions.

A dark green chalcedony speckled with blood-red spots of iron oxide, traditionally known as heliotrope.

A fossiliferous jasper packed with spiral snail shells, technically a silicified gastropod limestone from Wyoming.

A jasper marked with soft feather- or plume-like mineral inclusions that drift through a pale silica body.

A common opal containing moss- or fern-like mineral inclusions that resemble plants suspended in a pale silica body.