Fingerite

{{infobox mineral

| name = Fingerite

| image =

| alt =

| caption =

| category = Vanadate mineral

| formula = β-Cu₂V₂O₅

| IMAsymbol = Fgr{{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}}

| strunz = 8.BB.80

| dana =

| system = Triclinic

| class = Pinacoidal ({{overline|1}})
H-M symbol: ({{overline|1}})

| symmetry = P{{overline|1}}

| unit cell = a = 8.16, b = 8.27
c = 8.04 [Å]; α = 107.14°
β = 91.39°, γ = 106.44°; Z = 1

| color = Black; medium gray in reflected light

| habit = Subhedral or anhedral; equant or platelike; up to 150 μm

| twinning =

| cleavage = None

| fracture =

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| luster = Metallic

| streak = Dark reddish brown

| diaphaneity = Opaque

| gravity =

| density = 4.78

| polish =

| opticalprop = Biaxial

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| solubility = Dissolves in water

| impurities =

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| references = [http://rruff.geo.arizona.edu/doclib/hom/fingerite.pdf Fingerite in The Handbook of Mineralogy][http://www.mindat.org/min-1550.html Fingerite] on Mindat.org[http://webmineral.com/data/Fingerite.shtml Fingerite data on Webmineral]

}}

Fingerite is a copper vanadate mineral with formula: β-Cu₂V₂O₅. It was discovered as triclinic crystals occurring as volcanic sublimates around fumaroles in the crater of the Izalco Volcano, El Salvador.

Associated minerals include thenardite, euchlorine, stoiberite, shcherbinaite, ziesite, bannermanite, chalcocyanite and chalcanthite. The mineral also dissolves in water.{{Cite news |title=For a special Valentine? Beyond diamonds and gems: The world's rarest minerals |url=https://phys.org/news/2016-02-special-valentine-diamonds-gems-world.html |access-date=November 15, 2023}}

Fingerite is named for Dr. Larry W. Finger (1940–2024{{Cite web |date=2024-06-28 |title=Larry Finger – Hixson-Klein Funeral Home |url=https://hkfuneralhome.com/larry-finger/ |access-date=2024-06-28 |archive-url=https://web.archive.org/web/20240628100818/https://hkfuneralhome.com/larry-finger/ |archive-date=2024-06-28 }}) of the Geophysical Laboratory, Carnegie Institution of Washington.