Decades ago in a different job, I was tasked with cleaning out a bunch of old senior exercises in a basement storage area, and a lot of rocks got tossed. This one caught my eye, though, because of the color. The pink crystals are the gemstone tourmaline, and the lavender flakey crystals are a form of lithium-bearing mica called lepidolite. My best guess is that it came from one of the mines in the San Diego region of southern California.
Some deskcrops are not eye-catchers, but have special significance. These bladed crystals are samples of anorthoclase, from the pool of lava on at the summit of Mt. Erebus in Antarctica. It was collected by a researcher who spoke at our campus a few years ago, and was kind enough to donate the samples to the department.