Bring natural beauty to your home with a polished black agate wind chime. Agate is a naturally formed semi-precious gemstone that includes the minerals chalcedony and quartz. Each slab of agate is unique in structure and crystal habit, so one slab may have more layers of bands and another may have more visible crystals. All agates have crystalline structures, but some are cryptocrystalline, meaning you cannot see it with the naked eye, but you can under a microscope. Each agate slab measures at least 3 inches in length. The total length of the wind chime is approx. 25 inches.