Agates are a type of chalcedony, a microcrystalline form of quartz (SiO₂), known for their unique banding patterns and wide range of colors, including white, gray, blue, red, brown, and green. These colors and patterns are the result of mineral inclusions and variations in the deposition of silica. Agates are formed in volcanic rocks and cavities, often appearing as nodules or geodes. They have a Mohs hardness of 6.5 to 7, making them durable and suitable for jewelry, carvings, and ornamental use. Agates are commonly found in Brazil, Mexico, India, and the United States. Popular varieties include Moss Agate, Blue Lace Agate, and Dendritic Agate.