Rock & Mineral Encyclopedia

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

Sweetwater Agate

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

Obsidian colored brown by iron oxide inclusions, frequently banded or swirled with black as in mahogany obsidian.

A translucent chalcedony decorated with branching, fern-like manganese or iron oxide inclusions resembling tiny plants.

A pink, manganese-rich variety of zoisite used as an ornamental gemstone, often mottled with white quartz and grey matrix.