Chalcedony ps. After fossilized snail

Item Description

A super-rare and superb combination pseudomorph from this very obscure African locale. The perfectly fossilized spiral Turritella-like snail has been replaced by lustrous, translucent, brown chalcedony and white moganite, a very rare SiO2 modification, that is not uncommon as a minor component of finely crystalline chalcedony (as well as chert or flint) (MINDAT). The tip is slightly broken but I picked this from a small selection and most had quite a bit more damage. VERY RARE material. Value??