Identifying quartz: the most common mineral you will find

Quartz is one of the most abundant minerals on earth and the base material behind agate, jasper, amethyst, citrine, and chalcedony, all of which are technically quartz or cryptocrystalline quartz varieties. Pure quartz is a 7 on the Mohs scale, hard enough to scratch glass and most steel, which is one of the fastest field tests available. It has no cleavage, meaning it breaks with a curved, shell like conchoidal fracture rather than along flat planes, and clear specimens are colorless with a glassy luster. Crystal quartz often forms six sided prisms terminating in a point, though massive or water worn quartz shows no crystal form at all. Because it is so common and so hard, quartz survives weathering and stream transport extremely well, which is exactly why it shows up so often in gravel bars and desert washes long after softer minerals nearby have broken down.