Gormanite

{{Short description|Phosphate mineral}}

{{Infobox mineral

| name = Gormanite

| image = Gormanite-165270.jpg

| imagesize = 260px

| alt =

| caption = Gormanite from the Doce valley, Minas Gerais, Brazil (size: 4.2 × 4.2 × 3.0 cm)

| category = Phosphate minerals

| formula = {{chem2|(Fe,Mg)3Al4(PO4)4(OH)6*2H2O}}

| IMAsymbol = Gm{{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 = 8.DC.45

| dana =

| system = Triclinic

| class = Pedial (1)
(same H-M symbol)

| symmetry = P1

| unit cell = a = 11.77, b = 5.11
c = 13.57 [Å]; α = 90.45°
β = 99.15°, γ = 90.05°; Z = 2

| color = Blue green

| colour =

| habit = Aggregates of acicular crystals; pseudomonoclinic

| twinning = Polysynthetic around [010]

| cleavage = {001} indistinct

| fracture = Splintery

| tenacity = Brittle

| mohs = 4–5

| luster = Sub-vitreous, greasy

| streak = Pale green

| diaphaneity = Semitransparent

| gravity = 3.10–3.13

| density =

| polish =

| opticalprop = Biaxial (−)

| refractive = n_α = 1.619 n_β = 1.653 n_γ = 1.660

| birefringence = .041

| pleochroism = Strong, X colorless, Y blue, Z colorless

| 2V = Measured: 53°

| dispersion =

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| prop1 =

| prop1text =

| references = {{Mindat |id=1729 |name=Gormanite |accessdate = 2011-01-30}}{{WebMineral |name = Gormanite |url = http://webmineral.com/data/Gormanite.shtml |accessdate = 2011-01-30}}[http://rruff.geo.arizona.edu/doclib/hom/gormanite.pdf Handbook of Mineralogy]

}}

Gormanite is a phosphate mineral with the formula {{chem2|(Fe,Mg)3Al4(PO4)4(OH)6*2H2O}}. It was named after the University of Toronto professor Donald Herbert Gorman (1922–2020).