Musée des Cristaux - Espace Tairraz gives Chamonix's mountains a mineral close-up. The collection is strongest on crystals from the Mont Blanc massif, especially smoky and rose quartz, but it also reaches across the Alps and farther afield.
It is a good bad-weather stop, and a useful one before or after a lift ride. After looking at the specimens, the granite, ice, and scree outside feel less like scenery and more like a working geological machine.