Nearly complete joint face, with full plumose pattern, Tucson Mountains, AZ


I collected this in the mid-1970s in the Tucson Mountains.  It is not common to find a single small rock that has a complete joint surface, and with such a remarkable display of plumose features.

Age & Formation
Siliceous sedimentary rock within the Amole Arkose Formation of Lower Cretaceous age, ~120 Ma.