Rock & Mineral Encyclopedia

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

Wolframite

Wolframite is the historic principal ore of tungsten, a heavy black tungstate forming bladed crystals in granite veins.

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

A barium-bearing potassium feldspar intermediate between orthoclase and celsian, found in barium-rich metamorphic and ore deposits.

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

A black iron-manganese niobate that is a primary ore of niobium, forming a continuous series with tantalite (together called coltan).

A dark gray copper sulfide that is one of the richest copper ores, prized by collectors when found as rare sharp crystals.