Rock & Mineral Encyclopedia

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

Dacite

A fine-grained volcanic rock intermediate between andesite and rhyolite, common at explosive stratovolcanoes.

A dark, highly vesicular volcanic rock full of gas bubbles, denser than pumice, common as red or black lava rock.

A general field term for green, low-grade metamorphosed basaltic rocks colored by chlorite, epidote, and actinolite.