Agate is gemologically described as a cryptocrystalline variety of quartz. Rather than a single crystal, it is composed of miniature crystals that can only be seen with extreme magnification. In appearance agate is often banded. The concentric bands may be oval, rounded, elliptical, or totally irregular in shape, and may be multiple colors, or different shades of a single color. There are many different variations of agate which can be mined in Brazil, China, India and Madagascar to name a few.