Kayrobertsonite
Kayrobertsonite is an IMA-recognized mineral species in the phosphate class, with the chemical formula MnAl₂(PO₄)₂(OH)₂·6H₂O.
It crystallizes in the triclinic crystal system (space group P-1). It is a member of the Nordgauite structural group.
Key properties: Mohs hardness 2; specific gravity 2.29; Silky luster; optically biaxial.
IMA symbol Kay, IMA status: approved, named in 2015.
A late-stage hydrothermal mineral in pegmatite as part of a complex suite of Al-rich secondary phosphates.
It is found associated with Zwieselite-triplite, fluorapatite, nordgauite, whiteite-CaMnMn, members of the jahnsite group, morinite, fluellite, Al-bearing strunzite (Hagendorf).
The mineral was named to honor German-American mineral collector Gabriella Kay Robertson (b. 1920) of Los Angeles, California, USA. Since the mid-1950s.