Editing Columbite (section)

== Structure ==
Columbite atoms form an octahedral structure where [[niobium]] or [[tantalum]] atoms surround an oxygen atom. Overall, Columbite forms [[Orthorhombic crystal system|orthorhombic]] crystals which give approximate lengths of the crystal axes as a ≈ 14.27, b ≈ 5.73, and c ≈ 5.06 Å.<ref name=":2">{{Cite journal |last1=Balassone |first1=Giuseppina |last2=Danisi |first2=Rosa Micaela |last3=Armbruster |first3=Thomas |last4=Altomare |first4=Angela |last5=Moliterni |first5=Anna Grazia |last6=Petti |first6=Carmela |last7=Mondillo |first7=Nicola |last8=Ghiara |first8=Maria Rosaria |last9=Saviano |first9=Michele |date=2015-07-01 |title=An insight into crystal chemistry and cation order of columbite-(Fe) and columbite-(Mn) from worldwide occurrences |url=http://www.schweizerbart.de/papers/njma/detail/192/84961/An_insight_into_crystal_chemistry_and_cation_order?af=crossref |journal=Neues Jahrbuch für Mineralogie - Abhandlungen |language=en |volume=192 |issue=3 |pages=275–287 |doi=10.1127/njma/2015/0285 |issn=0077-7757}}</ref> Different columbite species such as manganocolumbite or ferrocolumbite can change the lengths of the crystal axes.<ref name=":2" />
[[File:Face-centered orthorhombic.png|thumb|195x195px|Face centered crystal structure of columbite (orthorhombic)]]
Since columbite can form species with other minerals, the physical properties of the mineral can change. When ferrocolumbite is introduced to heat, an equal expansion of the ‘a’ and ‘b’ axis occurs.<ref name=":2" /> In addition, due to the size of the ions and the overall structure, ferrocolumbite is more compressible than manganocolumbite.<ref name=":2" /> When manganocolumbite is introduced to heat, an expansion of the ‘a’ axis occurs resulting in an uneven change to the structure.<ref name=":2" />