Rock & Mineral Encyclopedia

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

Shadow Agate

A banded agate that displays a moving shadow or flash across its surface when tilted under light, caused by closely spaced parallel bands.

A warmly colored chalcedony agate with reds, oranges, golds, and pinks that blend like the glowing bands of a sunset sky.

A chalcedony agate with soft, billowing cloud-like masses of gray and white suspended in a translucent body.

A translucent Wyoming chalcedony filled with delicate black manganese dendrites that resemble tiny ferns, moss, or starbursts.

A translucent apple-green chalcedony colored by nickel, the most prized green variety of the quartz family.

A brecciated, chatoyant quartz with swirling blue, gold, and brown fibers that shimmer like a stormy sky.

A banded variety of chalcedony quartz, classically black or black-and-white, long favored for cameos and beads.

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

Rutile is a major titanium ore and the famous golden needle inclusion that gives rutilated quartz its shimmering threads.

A vivid blue-green hydrated copper silicate, soft on its own but prized as a gem when hardened by intergrown quartz or chalcedony.

A richly saturated green variety of elbaite tourmaline whose color rivals emerald, colored by trace iron, chromium, or vanadium.