Springfield,
Most likely it is San Miguel Chapel in Santa Fe, New Mexico.
Good luck,
Joe
Interesting idea, but since the treasure's name indicates that the church owns it, and all the churches in Santa Fe, NM, that pre-date the Mexican War were Franciscan, why then is the alleged Salt/Gila cache associated with the Jesuits? And the Peralta - Santa Fe connection? True, Pedro de Peralta founded and named Santa Fe, NM, in the early 17th century, but he was soon sent back to Mexico in chains, and there were no more prominent Peraltas in present New Mexico thereafter. Finally, the alleged size of the cache. Yes, there were comfortable Mexicans in Santa Fe in 1847, but their relatively modest assets came mostly from heavily taxing traders using the Santa Fe Trail and fur trappers who used Taos as their base. Northern New Mexico had little agricultural output, no manufacturing, and modest mining. The Franciscans struggled mightily just trying to convert the Natives. No, IMHO, Santa Fe, NM is not the inspiration for this alleged cache tale.
That said, I believe that the Franciscan association might still be in play here, if this Arizona cache legend is based on facts, that is, and not some trickster's fertile imagination. It all goes back to Marcos de Niza. IMO, 'The Church of Santa Fe' refers to something other than the capital city.