Columbite, also called niobite, niobite-tantalite and columbate [Nb₂O₆], is a black mineral group that is an ore of niobium. It has a submetallic luster and a high density and is a niobate of iron and manganese. This mineral group was first found in Haddam, Connecticut, in the United States.
Color: Black, brownish black
Crystal system: Orthorhombic crystal system
Crystal class: Dipyramidal (mmm); H-M symbol: (2/m 2/m 2/m)
Optical properties: Biaxial (+), b=2.29–2.4
Space group: Pbcn
Other characteristics: non-radioactive, non-fluorescent
Color: Black, brownish black
Crystal system: Orthorhombic crystal system
Crystal class: Dipyramidal (mmm); H-M symbol: (2/m 2/m 2/m)
Optical properties: Biaxial (+), b=2.29–2.4
Space group: Pbcn
Other characteristics: non-radioactive, non-fluorescent
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