columbite

{{Infobox mineral | name = Columbite | category = Oxide minerals | boxwidth = | boxbgcolor = | image = Columbite-75444.jpg | imagesize = 260px | caption = | formula = {{chem2|(Fe^{II},Mn^{II})Nb2O6}}, or in oxide formula {{chem2|(Fe^{II},Mn^{II})O*Nb2O5}} | IMAsymbol=Clb | molweight = | strunz = 4.DB.35 | system = Orthorhombic | class = Dipyramidal (mmm) H-M symbol: (2/m 2/m 2/m) | symmetry = Pbcn | color = Black, brownish black. | habit = Massive – granular – common texture observed in granite and other igneous rock; Striated - parallel lines on crystal surface or cleavage face. | cleavage = [010] Distinct | fracture = Sub-conchoidal: fractures developed in brittle materials characterized by semi-curving surfaces. | mohs = 6 | luster = Sub-metallic | refractive = | opticalprop = Biaxial (+), b = 2.29–2.4 | birefringence = | pleochroism = | streak = Blackish brown | gravity = 5.3–7.3 | melt = | fusibility = | diagnostic = | solubility = | diaphaneity = | other = 25px Radioactive, non-fluorescent. | references =

}} Columbite, also called niobite, niobite-tantalite and columbate, with a general chemical formula of {{chem2|(Fe^{II},Mn^{II})Nb2O6|auto=yes}}, is a black mineral group that is an ore of niobium. It has a submetallic luster, a high density, and is a niobate of iron and manganese. Niobite has many applications in aerospace, construction and the medical industry. Dating columbite minerals is primarily completed by uranium–lead dating, a slow process.