Shape & smooth texture of the stone, with a concave area on one side make for a good fidget/stress relief tool. Fits well in the hand, so inconspicuous, too.
I've purchased 3 of these - 1 for myself and the other 2 as gifts, primarily because I love chrysocolla. Typical of chrysocolla, each one has varied in color, all of which are very pretty. and nicely crafted.