About Columbite
Mineral formula: Fe2+Nb2O6 to Mn2+Nb2O6
Mineral group: member of the Columbite group
Crystal system: orthorhombic
Crystal habit: Short prismatic or equant, also flat tabular
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- Mineralogy and geology*
Cleavage: distinct on {100], less distinct on {010]
Fracture: irregular/uneven, subconchoidal
Color: black to brownish black
Luster: vitreous to sub-metallic
Diaphaneity: opaque
Moh’s scale hardness: 6
Streak: black to dark brown
Specific gravity: 5.2 – 6.65
Named: in 1801 by Charles Hatchett (1765-1847) from a specimen collected in the mid-17th century in a place called Nautneague (now regarded as Haddam, Connecticut, USA). The specimen was from the mineral collection of John Winthrop (1606–1676), governor of Connecticut and was given to Hans Sloane by John Winthrop (1681–1747) who was the grandson of the governor with the same name. From the type specimen, Hatchett named the new element columbium (now called niobium). The current species, columbite-(Fe) retains the old root name and has the suffix -(Fe) to indicate the dominance of iron in the species. Columbite was the second species named from the USA, after celestine (q.v.)
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* Mineralogical information is from mindat.org