Faulted chert nodule, Rincon Mountains, near Tucson, Arizona


I collected this in the late 1970s in the Rincon Mountains in the Happy Valley area.  It is one thing to find a small rock that is marked by a single fault, and quite another to find one with a system of faults.  I like the fact that by eye it is ‘easy’ to ‘unfault’ the rock and get back to the original shape and size of the chert nodule.  

Age & Formation
Horquilla Formation of Pennyslvanian age, ~310 Ma.