Jasper and hornblende have something in common: when in doubt, say it’s jasper. Although several different rocks and minerals can be greenish, reddish, or yellowish and have a smooth, waxy-looking surface, when they find a rock on the ground, many rockhounds will just assume “Oh, this must be jasper.” They’re not always wrong, because jasper is pretty common, but it could easily be something else, like quartzite, for example. Jasper can be made of chalcedony, a type of “cryptocrystalline” quartz that agate is made of, or a different type of cryptocrystalline quartz called “microgranular,” which is what flint is made of. Either way, when you look at jasper, you just see a smooth surface, not sharp-edged crystals. The reason people hope they’ve found jasper is that it’s a pretty hard mineral that polishes really well and can have interesting colors and patterns. It’s a popular mineral for making into jewelry and other decorations, and people have given it different names to describe where it came from or what it looks like, such as “picture jasper.”