Cyrilovite Locality: Hagendorf South Pegmatite (Cornelia Mine; Hagendorf South Open Cut), Hagendorf , Waidhaus , Vohenstrauß , Oberpfälzer Wald , Upper Palatinate , Bavaria , Germany ( Locality at mindat.org ) Picture width 1 mm. Collection and photograph Christian Rewitzer This Photo was Mindat.org Photo of the Day - 17th Jun 2008 — Photo: Christian Rewitzer · CC BY-SA 3.0
Cyrilovite
A hydrous sodium-iron phosphate of granitic pegmatites — the iron analogue of the aluminium mineral wardite.
Intro adapted from Wikipedia (CC BY-SA).
Cyrilovite is an IMA-recognized mineral species in the phosphate class, with the chemical formula NaFe³⁺₃(PO₄)₂(OH)₄·2H₂O.
It crystallizes in the tetragonal crystal system (space group P4_12_12). It is a member of the Wardite structural group.
Key properties: Mohs hardness 4; specific gravity 3.08–3.1; Yellow streak; Vitreous luster; refractive index 1.788; optically uniaxial.
IMA symbol Cyr, grandfathered status — known before the IMA’s founding, named in 1953.
Found as a rare accessory mineral in some oxidizing phosphate-bearing granite pegmatites and iron deposits.
It is found associated with Dufrénite, frondelite, phosphosiderite, leucophosphite, whitlockite, kingsmountite, triphylite, rockbridgeite, strengite, phosphosiderite, jahnsite.
The name refers to its occurrence in the Cyrilov pegmatite, Czech Republic.