Small dark blue crystals of nyboite in green jadeite. From: Palos Hill, Gria Spilia, Syros Island, Syros, South Aegean, Greece. — Photo: Leon Hupperichs · CC BY-SA 3.0
Nybøite
Nybøite is an IMA-recognized mineral species in the silicate class, with the chemical formula NaNa₂(Mg₃Al₂)(Si₇Al)O₂₂(OH)₂.
It crystallizes in the monoclinic crystal system (space group C2/m). It is a member of the Amphibole structural group.
Key properties: Mohs hardness 5–6; specific gravity 3.04; [Vitreous.] luster.
IMA symbol Nyb, IMA status: approved, named in 1981.
Found in a compositionally-layered eclogite that has undergone high-pressure amphibolite facies metamorphism (Nordfjord, Norway).
It is found associated with Taramite, omphacite, jadeitic clinopyroxene, aegirine-augite, paragonite, apatite, albite, garnet, epidote, kyanite, quartz, coesite (Lanshantou, China).
Apparently for the type locality, the NybÄo eclogite, Nordfjord, Norway.