I got the idea for this experiment while working on the rocks we collected recently. When we got home last weekend, we unloaded the 750 pounds of quartz crystals from our Arkansas trip onto the back patio. Then I left for Philadelphia to present some electricity shows. Today, I went out to unpack some of the boxes. We had wrapped the best crystals in newspaper, and all the newspaper that was exposed to sunlight had turned yellow. Cool! A chemical color change that happens fairly quickly, and is caused by exposure to light!