I've been to a few mineral museums like this and one of the interesting ones you can come across is Asbestos. Just hanging out there on display right next to some other mineral. It forms beautiful formations just like the rest, but I've heard so many mesothelioma lawyer commercials that it's easy to forget it's a completely natural material. Also one you can pick apart like cotton and weave into a fabric - it's a flexible material, made out of a rock, which can kill you.
The asbestos formations are ones they keep behind glass.
We used to have asbestos rocks sitting around in our house when I was growing up (my mother was born a raised in the town formerly called Asbestos, QC). You could just peel the fibers off the rock. In that form the asbestos is harmless: it's only when it's chopped into shorter fibers and inhaled that it's seriously unhealthy. Industrial uses almost always chopped the fibers so almost no commercial products using asbestos are safe, but the rocks just sitting there are harmless.