.....Tired of typing, but maybe you will get my point....
Mike, excellent post. I can tell you know your stuff. We might disagree on the 'treasure' implications of all this, but .... I am enjoying reading your stuff. I will only briefly comment here:
a) re.: "slaves": Bear in mind that the meaning of this word, in today's vocabulary and mental image, is of blacks in the American southwest prior to the CW. Eg.: stocks, bonds, whippings, blah blah. But there was a time when the word was more akin in meaning/effect of employee, or servant, etc... I do not want to enter a debate with anyone on this, and yes, I'm sure the world in the 1700s was harsh, cruel, etc... But you have to factor in the times. Things like corporal punishment, forced labor, etc... were not something unique to just one race or religion or class. It was world-wide at the time. Even the British navy could give a sailor 20 lashes for insubordination. Or tell them to "walk the plank". Heck, when I was a kid in the 1960s, we got a ruler across the knuckles for talking in class ! But today, an NFL player is front page news if he spanked his kid.
So what I'm saying is, if you think the fact of "slaves" meant "riches" (for whomever had "slaves"), this is not necessarily a given.
b) And as for all the church's land and cattle etc...: You have to remember that the church and the government were in a cooperative effort at the time (not the separation of church and state we have today). So the mission frontier posts (which might each have a detachment of soldiers stationed) administered the land on behalf of the crown. So it was really the crown (Spains) land. The riches (cattle, land, etc...) was only administered/over-seen by the church. It wasn't really the church's riches to do with what they pleased. Am I saying that they didn't have liberty to benefit from the resources ? Of course not. But don't think for a moment they weren't sincere about their religious convictions (to spread the gospel). It wasn't about mining, riches, prosperity, etc... If you read the accounts (from their own words) of the early missionaries (Serra, for instance), you will see that they were quite sincere. Could there have been bad apples ? Sure.
c) As for mines, (and supposed reams of gold brimming at the seams): An interesting factoid emerges from history, at least in-so-far as the CA missions are concerned: Spain , at one time early one (within the first decade of start the CA missions) was thinking of abandoning the alta CA effort. Why ? LACK OF NATURAL RESOURCES (mineral wealth, etc...) Kind of silly when you think about how much gold was eventually to be found during the CA gold rush, eh ? But at those earlier mission times, it was still, as of yet, unknown. So Serra implored Spain to not abandon the effort, and to continue on.
But let's just assume for the moment there was mines. Perhaps in NM, TX, AZ, and eventually CA, etc ... Ok, well sure: They harvested all sorts of prosperity from the land. Eg.: cattle, seal furs, mineral wealth, etc... Why wouldn't they ? They were administering on behalf of the crown after all. They had to subsist off their own resources after all.
But cut to the chase and ask yourself how much frickin' gold could you get by hand labor (EVEN WITH FORCED LABOR) back in those days ? I mean, heck, we have mechanized means nowadays, state-of-the-art metal detectors, etc... And most hobbyists, even with such advanced abilities to get nuggets, process ore, etc... are LUCKY to get a profitable amount. Right ? Even full-bore mining operations that process ore on a grand scale (with advanced abilities to find the most profitable regions, shafts, etc...) will work their tails off to make a single bar of gold (having processed thousands upon thousands of cubic yards of material to get that !).
So ...somehow ... because you see a few lone shafts that dot the desert now, and you could (if you did) find out they were Spanish era dated, and ....... somehow this equates to "gold stacked to the ceiling" ? I'm sorry, but if they can't do it now, with all the advances we have at our disposal, how did they just magically just find caves with naturally occurring fist sized nuggets all over back then ? It just defies all mining logic.