Rock & Mineral Encyclopedia

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

Bloodstone

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

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

The principal iron ore, a heavy iron oxide ranging from metallic silver-gray to earthy red, always leaving a tell-tale red-brown streak.

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

A green-and-red ornamental stone of epidote and red piemontite or iron oxide, named for its dragon-skin coloring; not a true jasper.

A bright red mercury sulfide, the chief ore of mercury and the historic source of the pigment vermilion.