Dust, mold and pests
Updated
The mundane group, and the one where the damage falls on the documentation rather than the stone.
Dust is abrasive
Settled dust dulls a specimen and holds moisture against it. Both matter over decades.
The removal is where the damage happens: wiping dust off a crystal face drags grit across it. Blowing or a soft brush, not a cloth.
Closed storage solves it, at the cost of concentrating whatever the enclosure gives off, which is the trade this whole section keeps returning to.
Mold needs organics
Minerals do not support mold. Everything around them does: paper labels, cardboard boxes, cotton wadding, wooden mounts, cork.
Above about 65% RH with poor air movement, mold appears on the packing and then on the labels, which is where the loss is.
The fix is humidity and air movement rather than anything applied to the specimens.
Pests eat the labels
Silverfish and booklice eat paper and the starch in adhesives. They have no interest in the mineral and every interest in the documentation.
Which makes an infestation in a mineral collection a data loss event, and it is the reason a catalog kept elsewhere matters.
Look for grazed label edges, tiny holes and frass in drawer corners.
Keeping it clean
Moderate humidity and some air movement handle almost all of it.
Inert plastic rather than cardboard for boxes, which removes both the food and the acid.
Inspect annually, drawer by drawer. The same pass that catches pyrite decay catches this.
And keep food out of the collection room, which sounds beneath mentioning and is how most infestations start.