An unusual specimen in that the significant crystal of carrollite here is shaped more like an extended cube (with bevelled edges) than the usual octahedral forms we see. So, this is a rare crystal habit, even for those who already have an example of the species. Few world class pockets of this rare cobalt species have been found over the years, and generally most specimens are found as single crystals without good matrix. Matrix specimens of any quality are rare and those on contrasting white calcite, moreso. Not only is this metallic mirror-like crystal perched on calcite, but it is on CRYSTALLIZED calcite, an important distinction that sets it above most others that are simply embedded in massive white calcite (presumably the calcite came later, and filled the pockets, overlapping and enclosing most specimens). Luster is fabulous, the geometric shape is eye catching, and the balance of colors here makes it pop to the eye. Overall an extremely fine example of this rare species. Large crystal measures 3 x 2 x approx. 2 cm in size, and others are up to about 1 cm. Overall, a very rare, and important older specimen probably from finds back in the early 2000s and we found it in an old dealer stock in Europe.