Ore mineral for tungsten, with the formula (Fe,Mn)WO4; sp. gr. 7.0–7.5; hardness 5.0–5.5; monoclinic; grey-black to brownish-black; brownish-black streak; metallic lustre; crystals normally tabular, prismatic, often bladed, also occurs granular and massive; cleavage perfect {010}; occurs in high-temperature hydrothermal veins, quartz veins, and pegmatites, associated with granitic rocks, with cassiterite, arsenopyrite, tourmaline, scheelite, galena, sphalerite, and quartz.