Article · Wikipedia archive · Last revised Jun 18, 2026

Strengite

Strengite is a relatively rare iron phosphate mineral with the formula: FePO4·2H2O. The mineral is named after the German mineralogist Johann August Streng (1830–1897). Lavender, pink or purple in hue, it is similar to variscite and is partially soluble, particularly in conditions where there is a low pH and low oxidation-reduction potential. The color comes from ferric ion (Fe3+).

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Jun 18, 2026
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Strengite
A small crystal of Strengite
General
CategoryMinerals
FormulaFePO4·2H2O
IMA symbolStg1
Strunz classification8.CD.10
Dana classification40.04.01.02
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H-M Symbol: (2/m 2/m 2/m)
Space groupPcab
Identification
Formula mass186.85 g/mol
ColorColorless, pale violet, deep violet, red, carmine red, greenish white
Crystal habitBotryoidal, radial, spherical
Cleavage{010} Good, {001} Poor
Mohs scale hardness3.5–4
LusterVitreous
StreakWhite
DiaphaneityTransparent to translucent
Specific gravity2.84
Density2.87 g/cm3
Optical propertiesBiaxial (+)
2V angle72° – 88°
Dispersionr < v, relatively strong
References234

Strengite is a relatively rare iron phosphate mineral with the formula: FePO4·2H2O.5 The mineral is named after the German mineralogist Johann August Streng (1830–1897).6 Lavender, pink or purple in hue, it is similar to variscite7 and is partially soluble, particularly in conditions where there is a low pH and low oxidation-reduction potential.5 The color comes from ferric ion (Fe3+).8

References

References

  1. Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. "Strengite Mineral Data". Webmineral.com. Retrieved 2011-10-25.
  3. "Strengite mineral information and data". Mindat.org. Retrieved 2011-10-25.
  4. "STRENGITE (Hydrated Iron Phosphate)". Retrieved 2011-10-25.
  5. Patrick, W. H. Jr.; Gotoh, S.; Williams, B. G. (February 9, 1973), "Strengite Dissolution in Flooded Soils and Sediments", Science, 179 (4073): 564–565, Bibcode:1973Sci...179..564P, doi:10.1126/science.179.4073.564, PMID 17820817, S2CID 29895850
  6. Senning, Alexander (2007), Elsevier's dictionary of chemoetymology: the whies and whences of chemical nomenclature and terminology, Elsevier, p. 374, ISBN 978-0-444-52239-9
  7. Pough, Frederick H.; Peterson, Roger Tory (1997), A Field Guide to Rocks and Minerals, Peterson Field Guide, vol. 7 (5th ed.), Houghton Mifflin Harcourt, p. 239, ISBN 0-395-91096-X
  8. "Minerals Colored by Metal Ions". minerals.gps.caltech.edu. Retrieved 2023-03-01.