WARNING
Five minute research from a guy with zero geology insight. Please edit to make this respectable!
Excerpts from http://docs.azgs.az.gov/SpecColl/2008-01/2008-01-0426A.pdf

The Stronghold Granite is a fresh, subvolcanic intrusive with minor iron in some of the ferromag sites and along an occasional fracture. The Cochise Peak quartz monzonite is essentially fresh, though undoubtedly slightly thermal metamorphosed by the Stronghold Granite. Most of the ferromag sites have been converted to iron oxide and epidote is found on the fractures.

X-ray fluorescent spectrographic analyses show the Stronghold Granite to be impoverished in strontium with respect to other analyzed granites of similar calcium content and higher in the ratio of calcium over strontium.