Rock & Mineral Encyclopedia

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

Lodestone

A naturally magnetized variety of magnetite that attracts iron, historically used as the first magnetic compass.

A naturally magnetic black iron oxide and a major iron ore; strongly magnetic specimens are known as lodestone.

A metamorphosed banded iron formation of alternating quartz and iron-oxide layers, mined as a major iron ore.

A banded, metamorphosed iron formation in which bright red jasper alternates with silvery hematite or magnetite layers.

A bronze-colored iron sulfide notable for being the most magnetic of the common sulfide minerals and an important nickel host.

A black spinel-group zinc iron oxide, essentially unique to Franklin, New Jersey, where it was a key zinc and manganese ore.