Outstanding brown crystals of the very rare phosphate mineral gayite associated to white morinite from Portugal (Assunção Mine, Aldeia Nova, Sátão, Viseu District, Portugal). Ex. Erich Laskowski collection (USA). — Photo: David Hospital · CC BY 4.0
Gayite
Gayite is an IMA-recognized mineral species in the phosphate class, with the chemical formula NaMnFe₅(PO₄)₄(OH)₆·2H₂O.
It crystallizes in the monoclinic crystal system (space group C2/c). It is a member of the Dufrénite structural group.
Key properties: Mohs hardness 4–5; specific gravity 3.15; Olive green streak; Vitreous luster; optically biaxial.
IMA symbol Gy, IMA status: approved, named in 2008.
Found in vugs in hydrothermal apatite-(CaF) in a zoned granitic pegmatite.
It is found associated with Morinite, natrodufrénite, quartz, apatite-(CaF).
The mineral was named to honor Hebe Dina Gay (b. 1927), Professor Emeritus of Mineralogy, National University of Córdoba, Argentina, whose accomplishments include a 60-year career in teaching.