Rock & Mineral Encyclopedia

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

Dendritic Opal

A common opal with branching, tree-like mineral inclusions that create natural fern, moss, or landscape patterns.

A soft-toned cream-to-butterscotch jasper colored by iron oxides, prized by lapidaries for its smooth, even, opaque finish.

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

A red-toned banded chalcedony colored by iron oxides, ranging from natural carnelian-like reds to heat-treated stones.

A dark green jasper-chalcedony speckled with red iron-oxide spots, classically known as bloodstone or heliotrope.

A deep red banded agate colored by iron oxides, valued as a vivid red lapidary and jewelry stone.

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

A brownish-red to deep brown variety of chalcedony, closely related to carnelian but darker, colored by iron oxides.

A warm orange-to-red variety of chalcedony quartz colored by iron oxide, used since antiquity for seals, beads, and cabochons.