Brazilian Agates are found in the southern states in basalt formations from 4 to 40 feet deep and at elevations of about 2500 to 3500 feet above sea level. Agate is a variety of silica composed of alternating layers of various colored chert or quartz. Agates were named after the Acate River in Greece where the stones were originally found. The most accepted theory as to how these Agates formed is that as lava cooled, gas and steam accumulated to form bubbles or cavities. For many eons, water that carried silica penetrated the copper and iron-bearing rock surrounding the cavities, filling them with irregular internal layers. Finally, the whole mass hardened, ending a 50 million-year-long process and leaving beautiful, interesting stones for collectors to find and enjoy.