These are old European classics, that once puzzled the early mineralogists until it was understood that these unusually sharp green crystals were Malachite as perfect replacements of earlier Cuprite crystals. This is a rather large example, unusual in that it has evenly distributed and uniform color across all faces, without the usual pitting or etching often seen on any examples of this material over 1 cm or so. It is extremely large, to be so perfectly formed and sharp. Likely an older specimen, we know these were found as far back as the 1700s. This is a very large thumbnail, larger than nearly any other we have seen for sale in fact - but it is the uniformity of the dark and pleasing color that really takes this to another level more so than the size.