A very rare old classic of this copper/zinc arsenate, from an old location that is probably where it was first found, but not first recognized as a new species from. The theiseite is the chatoyant, deep green material you can see around the rim of the pocket, lined with a secondary growth of the same or perhaps of malachite, and on which small azurite blades perch. Small world that it is, the species is named after fellow Dallas collector and club member, Nick Theis, here in Dallas. Obviously it was found in the ground long before it was recognized as a new species, and named. This piece is, I am told, probably 120-160 years old.