Outstanding yellow acicular spherical aggregate of the very rare mineral phosphofibrite from the type locality in Clara mine (Clara Mine, Oberwolfach, Freiburg Region, Baden-Württemberg, Germany). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Phosphofibrite
Phosphofibrite is an IMA-recognized mineral species in the phosphate class, with the chemical formula (H₂O,K)₃.₅Fe³⁺₈(PO₄)₆(OH)₇·5H₂O.
It crystallizes in the orthorhombic crystal system. It is a member of the Phosphofibrite structural group.
Key properties: Mohs hardness 4; specific gravity 2.9; Vitreous luster; optically biaxial.
IMA symbol Pfb, IMA status: approved, named in 1982.
Found in a hydrothermal polymetallic barite–fluorite deposit.
It is found associated with Beraunite, strengite, barian pharmacosiderite, quartz.
The name refers to phosphorus in the composition and its characteristic fibrous habit.