Agates are a type of microcrystalline quartz (chalcedony) known for their colorful bands, unique patterns, and layered beauty. They usually form inside lava bubbles or cavities in sedimentary rocks, where silica-rich water deposits layer after layer of minerals over time. Each band you see in an agate represents a moment in geological time—like tree rings made of stone! Their colors range from earthy browns and reds to vibrant blues, purples, and even rainbows, depending on the minerals present during formation. No two agates are exactly alike, which makes each one a miniature natural artwork.