ferrimolybdite

{{infobox mineral

| name = Ferrimolybdite

| image = Ferrimolybdite-154908.jpg

| alt =

| caption = Ferrimolybdite crystals from the Kingman District, Mohave County, Arizona

| category = Molybdate mineral

| formula = Fe³⁺₂(MoO₄)₃·8(H₂O) or Fe³⁺₂(MoO₄)₃·n(H₂O)

| IMAsymbol = Fmyb{{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 =

| strunz = 7.GB.30

| dana =

| system = Orthorhombic

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

| symmetry = Pmmn

| unit cell = a = 6.665, b = 15.423
c = 29.901 [Å]; Z = 8

| color = Canary-yellow, straw-yellow, greenish yellow

| habit = Acicular tufted to radial aggregates; powdery, earthy

| twinning =

| cleavage = Distinct on {001}

| fracture = Uneven

| tenacity =

| mohs = 1-2

| luster = Adamantine, silky, earthy

| streak = Light yellow

| diaphaneity = Transparent to translucent

| gravity = 2.99

| density =

| polish =

| opticalprop = Biaxial (+)

| refractive = n_α = 1.720 - 1.810 n_β = 1.730 - 1.830 n_γ = 1.850 - 2.040

| birefringence = δ = 0.130 - 0.230

| pleochroism = X = Y = clear to nearly colorless; Z = dirty gray to canary-yellow

| 2V = 26° to 32° (calculated)

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| references = [http://www.mindat.org/min-1623.html Ferrimolybdite on Mindat.org][http://rruff.info/doclib/hom/ferrimolybdite.pdf Ferrimolybdite on the Handbook of Mineralogy][http://www.webmineral.com/data/Ferrimolybdite.shtml Ferrimolybdite data on Webmineral.com]

}}

Ferrimolybdite is a hydrous iron molybdate mineral with formula: Fe³⁺₂(MoO₄)₃·8(H₂O) or Fe³⁺₂(MoO₄)₃·n(H₂O). It forms coatings and radial aggregates of soft yellow needles which crystallize in the orthorhombic system.