Outstanding brown crystal aggregates of the extremely rare nickel mineral bonaccordite from the type and only known locality worldwide (Scotia Talc Mine, Bon Accord, Barberton, Ehlanzeni District, Mpumalanga Province, South Africa) and associated to green trevorite crystals. Ex Vandenbroucke Museum collection from Waregem, Belgium. — Photo: David Hospital · CC BY-SA 4.0
Bonaccordite
A rare nickel-iron borate of the ludwigite group, discovered in 1974, typically crystallizing as long prisms inside its host.
Intro adapted from Wikipedia (CC BY-SA).
Bonaccordite is an IMA-recognized mineral species in the borate class, with the chemical formula Ni₂Fe³⁺O₂(BO₃).
It crystallizes in the orthorhombic crystal system (space group Pbam). It is a member of the Ludwigite structural group.
Key properties: specific gravity 5.17.
IMA symbol Bna, IMA status: approved, named in 1974.
Found in a small tabular body of nickeliferous serpentinite, probably a contact deposit, along the junction of quartzite and an ultramafic intrusive; it appears to have formed at ∼730 ° C and < 2 kbar during thermal metamorphism.
It is found associated with Trevorite, liebenbergite, nepouite, nimite, bunsenite, gaspéite, violarite, millerite.
The name is derived from the locality at Bon Accord, South Africa.