Banded Agate Tapestry: Nature's Artistry in Stripes and Swirls Banded agates, essentially layered formations comprising quartz and chalcedony, represent an intriguing combination of these two minerals. While they possess an opaque quality, their distinct formation process imbues them with a unique appearance unlike other varieties. Upon closer inspection, microscopic quartz crystals become apparent, particularly notable in banded agates.