This Smithsonite has been tinted red-pink by Manganese rather than the usual Cobalt, which gives pink Smithsonite its unique color, similar to what's found at other localities. Pink Smithsonite is already rare, making this variation all the more special.

Previously, Manganoan Smithsonite was commonly mislabeled as Cobaltian Smithsonite in old collections before it was realized these unique pieces were colored by Manganese instead of Cobalt.

The small amount of manganese substituting for zinc constrains the crystal shape, and so they are somewhat sharper rhombohedra-like crystals than the normal styles of Smithsonite from Tsumeb and the resulting color is a red-pink, so distinct once you have seen these and compared them in person to the more common pink Smithsonite styles. 

Tsumeb Mine, Oshikoto Region, Namibia