A Pink Muscovite with Reverse Pleochroism from Archer's Post, Kenya¹ Available to Purchase

A pink muscovite from a manganese-bearing hydrothermal vein near Archer's Post, Kenya,has the following optical properties: α = 1.564, β = 1.600, γ = 1.605, 2V = 41°56′; and a distinct reverse pleochroism in thick sections, with X = rose pink, Y = pale orange-pink, Z = pale yellow. The stacking polytype is 2M₁. Specific gravity = 2.89.

Mössbauer and optical absorption spectra indicate that the pink color and the reverse pleochroism are due to tetrahedral Fe³⁺ and octahedral Mn³⁺