Strengite

Strengite is a relatively rare iron phosphate mineral with the formula: FePO₄ · 2H₂O.[4] The mineral is named after the German mineralogist Johann August Streng (1830–1897).[5] Lavender, pink or purple in hue, it is similar to variscite[6] and is partially soluble, particularly in conditions where there is a low pH and low oxidation-reduction potential.[4]

Strengite
A small crystal of Strengite
General
Category	Mineral
Formula (repeating unit)	FePO4 · 2H2O
Strunz classification	8.CD.10
Dana classification	40.04.01.02
Crystal system	Orthorhombic
Crystal class	Dipyramidal (mmm) H-M Symbol: (2/m 2/m 2/m)
Space group	Pcab
Identification
Formula mass	186.85 g/mol
Color	Colorless, pale violet, deep violet, red, carmine red, greenish white
Crystal habit	Botryoidal, radial, spherical
Cleavage	{010} Good, {001} Poor
Mohs scale hardness	​3 ^1⁄2 - 4
Luster	Vitreous
Streak	White
Diaphaneity	Transparent to translucent
Specific gravity	2.84
Density	2.87 g/cm^3
Optical properties	Biaxial (+)
2V angle	72° - 88°
Dispersion	r < v, relatively strong
References	[1][2][3]

References

1. "Strengite Mineral Data". Webmineral.com. Retrieved 2011-10-25.
2. "Strengite mineral information and data". Mindat.org. Retrieved 2011-10-25.
3. "STRENGITE (Hydrated Iron Phosphate)". Retrieved 2011-10-25.
4. 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
5. 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
6. Pough, Frederick H.; Peterson, Roger Tory (1997), A Field Guide to Rocks and Minerals, Peterson Field Guide, 7 (5th ed.), Houghton Mifflin Harcourt, p. 239, ISBN 0-395-91096-X