Regarding these rare silver minerals from the San José Mine I am seriously questioning this occurrence.
I visited this very modern and big mine a few weeks ago and was even lucky enough to meet their geologist. I was told that they are mining a very low grade ore, basically Acanthite (hardly visible by the naked eye!) in Quartz, with an average content of just 40gr Ag and 2 gr Au per ton. I showed him a few photos of minerals supposedly from there. To my big surprise, he said he had in all his years working here NEVER seen something similar. Not even "plata roja" (Proustite/Pyrargyrite) which is easily identifiable, even by amateurs!
Security measures are so strict that I was not even allowed to pass the door to the "patio" - HE had to come out to the parking lot to have a talk!
Based upon all that, my guess is, San José after all is just a camouflage and all these rare silver minerals are produced somewhere else.
This discussion of Minsur opens up a possible pandora of discussion.
I will note that last September, at the 2018 Denver show, my buddy, a fossil expert, and I saw 2 display cases of incorrect examples. One was a fossil/mineral combo which does not occur at the given locality and the other display case had a totally wrong locality given for one of the displayed minerals. We decided to do nothing regarding the mistakes in both cases.
Years ago, I was talking to one of the managers of the Huanzala mine in Peru, the mine which (according to Rock Currier's assessment) has produced more tonnage of crystallized mineral specimens than any other in the world (mostly pyrite crystals, but also some fluorite and many other species). This mine manager told me with a straight face that he didn't think any specimens came from Huanzala at all, because he had been underground many times and only seen massive ore, never a vug with crystals!
1) Vugs with crystals are much more rare in nature than collectors think.
2) The miners know where to find these rare vugs; the mine managers don't have a clue.
3) If a mine prohibits collecting, a miner selling a rock from there has an incentive to lie and say it came from somewhere else. There is no logical incentive to do the reverse, so if they say it came from a mine with a no-collecting policy, it probably did.
4. Mine managers and high level salaried employees have every reason to dissemble on specimen production...they look bad to their bosses if they admit it happens and invite more collecting if word gets out the miners can recover valuable specimens on the job.
John's question of which San Jose is in question is well taken. The San Jose silver mine in Oaxaca where these specimens come from has an average grade 7 times higher than the quoted 40 grams per tonne.
The mine I visited is very close to the village of Ocotlán, near Oaxaca.
Alfredo's point of view is so far really intriguing, but by no way surprising.