Tapiolite

{{Infobox mineral

| name = Tapiolite

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| image = Tapiolite-121701.jpg

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| formula = (Fe, Mn)(Nb, Ta)₂O₆

| IMAsymbol = Tap{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|journal=Mineralogical Magazine|volume=85|issue=3|pages=291–320|doi=10.1180/mgm.2021.43|bibcode=2021MinM...85..291W|s2cid=235729616|doi-access=free}}

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| system = Tetragonal

| class = Ditetragonal dipyramidal (4/mmm)
H-M symbol: (4/m 2/m 2/m)

| symmetry = P4₂/mnm

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| references = [https://www.mineralienatlas.de/lexikon/index.php/MineralData?mineral=Tapiolite Mineralienatlas]

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Tapiolite [(Fe, Mn)(Nb, Ta)₂O₆] is a black mineral series that is an ore of niobium and tantalum. The tapiolite group includes tapiolite-(Fe) or ferrotapiolite and tapiolite-(Mn) or manganotapiolite.[http://www.mindat.org/min-3887.html Mindat tapiolite group][http://rruff.info/doclib/hom/ferrotapiolite.pdf Ferrotapiolite in the Handbook of Mineralogy][http://rruff.info/doclib/hom/manganotapiolite.pdf Manganotapiolite in the Handbook of Mineralogy] Tapiolite-(Fe) is by far the more common of the two.[http://www.mindat.org/min-1531.html Tapiolite-Fe on Mindat][http://www.mindat.org/min-2523.html Tapiolite-Mn on Mindat]

The minerals have a submetallic luster and a high specific gravity with tapiolite-Fe having a higher specific gravity (7.90) versus 7.72 for tapiolite-Mn.

The mineral was named in 1863 after the forest god Tapio of Finnish mythology, and the original tapiolite material came from Sukula, Tammela, Tavastia Proper, Finland.[http://webmineral.com/data/Tapiolite.shtml webmineral Tapiolite]

Tapiolite is very close to columbite and tantalite. Those minerals have the same chemical composition, but different crystal symmetry orthorhombic for tantalite or columbite and tetragonal for tapiolite.P. Cerny et al. "The tantalite-tapiolite gap: natural assemblages versus experimental data" Canadian Mineralogist 30 (1992) 587 [http://rruff.geo.arizona.edu/doclib/cm/vol30/CM30_587.pdf free download]

{{Gallery

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|File:Tapiolite.GIF|Crystal structure of tapiolite

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