Gorgeous: Strange colors on rocks

fluorescent rock -Sterling Hill Mining Museum, NJ, USA, originally uploaded by Vilseskogen.

In northern New Jersey, USA, is a little mine called Sterling Mine, now a museum, filled with unusual rocks that have UV fluorescence. We walked into the mine, which is literally horizontally into a mountain wall, and then our guide turned off all lights. After a few seconds he turned on his black light (UV) and we were surrounded by glowing red and light green on the rock walls. Eerie, yes. Beautiful, yes. Could people have known about this before electricity and light bulbs? Are there more things like this that we do not yet know about because we don't' have the tools to see them? I wonder about things like this when I go on my walks, and I think that maybe what we see and perceive is maybe just a tiny bit of the reality that is surrounding us. The photo is from the Sterling Mine Museum, a must see place, where they have a whole room with rocks that fluoresce in different colors.