Fabianite

{{short description|Borate mineral}}

{{Infobox mineral

| name = Fabianite

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| category = Phylloborates

| formula = CaB₃O₅(OH)

| IMAsymbol = Fbn{{Cite journal|last=Warr|first=L.N.|date=2021|title=IMA–CNMNC approved mineral symbols|url=https://www.cambridge.org/core/journals/mineralogical-magazine/article/imacnmnc-approved-mineral-symbols/62311F45ED37831D78603C6E6B25EE0A|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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| strunz = 6.FC.20

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| system = Monoclinic

| class = Prismatic (2/m)
(same H-M symbol)

| symmetry = P2₁/a

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Fabianite is a borate mineral with the chemical formula CaB₃O₅(OH). It is colorless and leaves a white streak. Its crystals are monoclinic prismatic. It is transparent and fluorescent. It has vitreous luster. It is not radioactive. Fabianite is rated 6 on the Mohs Scale. It was named for Hans-Joachim Fabian, a German geologist.