tungstite

{{Short description|Hydroxide mineral}}

{{Infobox mineral

| name = Tungstite

| category =

| boxwidth =

| boxbgcolor =

| image = Tungstite on ferberite.jpg

| imagesize = 250px

| caption = Bright yellow tungstite on ferberite

| formula = WO₃·H₂O

| IMAsymbol = Tgs{{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}}

| molweight = 249.86 g/mol

| strunz = 4.FJ.10

| system = Orthorhombic

| class = Dipyramidal (mmm)
H-M symbol: (2/m 2/m 2/m)

| symmetry = Pmnb

| color = Yellow, yellowish green/orange

| habit = Earthy, pulverulent

| twinning =

| cleavage = Perfect along [001], imperfect along [110]

| fracture =

| tenacity =

| mohs = 2.5

| luster = Resinous, pearly

| polish =

| refractive = n_α = 2.090, n_β = 2.240, n_γ = 2.260

| opticalprop = Biaxial (-)

| birefringence = δ = 0.170

| dispersion = r < v (strong)

| pleochroism =

| fluorescence=

| absorption =

| streak = Yellow

| gravity = 5.517

| density =

| melt =

| fusibility =

| diagnostic =

| solubility =

| diaphaneity = Transparent

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Tungstite is a hydrous tungsten oxide mineral with formula: WO₃·H₂O. It is a secondary mineral formed by the weathering of other tungsten containing minerals. It crystallizes in the orthorhombic system in translucent yellow to yellow green masses. It is clay-like with Mohs hardness of 2.5 and a specific gravity of 5.5.

It was first described in 1868 for an occurrence near Trumbull, Connecticut at the Hubbard Tungsten Mine at Long Hill.