Rock & Mineral Encyclopedia

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

Feather Jasper

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

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

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

A common opal colored green by nickel or chromium impurities, usually opaque and cut into cabochons and beads.

A patterned common opal with mottled, leopard-like spots and blotches, prized as an ornamental and cabochon stone.

Aquamarine that shows a bright moving band of light, or cat's eye, caused by parallel needle-like inclusions when cut as a cabochon.

A chromium-dominant tourmaline related to dravite, producing intensely deep green to blackish-green crystals from chromium-rich metamorphic rocks.

A fine-grained sedimentary rock of compacted clay and silt that, unlike shale, breaks in blocks rather than thin layers.