The nickel-rich aluminous serpentine mineral originally called nimesite has been renamed brindleyite in honor of Professor G. W. Brindley. Brindleyite is a green clay-like mineral occurring adjacent to the footwall limestone at the base of the Marmara karstic bauxite deposits in Greece.
The new mineral is closely related in structure and stacking sequence to berthierine; it occurs as mixtures of the group A and group С polytypes of Bailey (1969). Spectroscopic data indicate that both natural and synthetic samples have a disordered cation arrangement. As expected, the green color of the mineral is due to octahedrally-coordinated Ni2+ ions. The structural formulae of brindleyites approximate to (Ni1.75Al1.0) (Si1.5Al0.5)O5(OH)4, and all analyzed samples showed a deficit in octahedral cations. Brindleyites exhibit a two-stage dehydroxylation process similar to that shown by amesite and other serpentine minerals.