Ferberite

Ferberite is a mineral from the wolframite group, composed of iron tungstate (FeWO₄). It occurs as prismatic or tabular crystals, ranging in color from black to brownish-black, with a submetallic to resinous luster.

Found in tungsten-rich hydrothermal veins, it is often associated with quartz, scheelite, cassiterite, or fluorite. The finest specimens, particularly those from China, Peru, Bolivia, and Portugal, are prized for their massive crystals, high density, and elegant crystalline morphology.