Geographic Minerals



Delvauxite, also known as borickite, is a yellow to brown to dark brown amorphous mineral, sometimes forming a botryoidal mass. It is a mineral approximately consisting of an ill-defined hydrous phosphate of iron. Its chemical formula is CaFe4(PO4, SO4)2(OH)8•(4-6)H2O. It may sometimes form stalactites.

It was first described in 1838 by a Belgian chemist, Dumont and dedicate to J.S.P.J. Delvaux de Fenffe (1782–1863). It was found in Bernau, Liege, Belgium and Stredocesky, Czech Republic.

General Information

  • Category: Phosphate minerals
  • Formula: CaFe4(PO4, SO4)2(OH)8(4-6)H2O.
  • Color: Yellow to brown to dark brown
  • Lustre: Vitreous, Waxy, Greasy
  • Specific Gravity: 1.85
  • Crystal System: Amorphous


Delvauxite is a yellow or brown amorphous mineral, sometimes forming a botryoidal mass or stalactites.

  • Transparency: Translucent, Opaque
  • Streak: Yellow, pale brown
  • Hardness: 2½ on Mohs scale
  • Fracture: Conchoidal
  • Density: 1.85 g/cm3 (Measured)
  • Cleavage: None

Occurrence: In gossan (Nenaˇcovice, Czech Republic).

Association: Diadochite, vivianite, pitticite, melanterite, “limonite”.


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