Yellow brown crystals of the very rare mineral wilhelmvierlingite associated to rockbridgeite from Germany (Hagendorf South Pegmatite, Bavaria, Germany). Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY 4.0
Wilhelmvierlingite
Wilhelmvierlingite is an IMA-recognized mineral species in the phosphate class, with the chemical formula CaMn²⁺Fe³⁺(PO₄)₂(OH)·2H₂O.
It crystallizes in the orthorhombic crystal system. It is a member of the Overite structural group.
Key properties: Mohs hardness 4; specific gravity 2.58; Pale yellow streak; Vitreous luster; optically biaxial.
IMA symbol Wvl, IMA status: approved, named in 1982.
Found as a rare secondary mineral in a complex zoned granite pegmatite.
It is found associated with Rockbridgeite, zwieselite.
The mineral was named to honor Wilhelm Vierling (1901–1995), Weiden, Germany, a longtime student of Hagendorf minerals.