This polished nodule of silicified (quartz-infused) chrysocolla is certainly one of the finest I have seen.I showed it to some Arizona experts and they agreed its among the best examples of this type seen. It is not carving grade because of the amount of quartz in it as opposed to chrysocolla, so it won't cut even blue cabochons. However, that makes it all the better as a specimen from our point of view, I think. The rich blue-green color and the depth of the "gem silica" through the quartz-rich zones are both remarkable. These are not common in such quality and make a neat accent to a collection of southwest mineral specimens, I think.