Very fine important example for this rare copper species from the USA. This is a crystal cluster of the rare copper arsenate, Euchroite. The crystals in this thumbnail have very good luster, a rich, deep green color, and they are translucent to gemmy. Such good characteristics are uncommon, no matter what the size of the Euchroite. Excellent thumbnail overall. It was collected by Bart Cannon, a well known collector of NE US minerals, in the 1970s