Agate is in the quartz family, composed primarily of microscopic crystallized silica (SiO2). It has curved bands, or zones, of differing color. Some agate slices are treated with different compounds and heated to give them brilliant blue, green and red colors. These specimens have been sawed and polished. Each Agate Slice is unique and will vary in shape, size and appearance. No two specimens will be exactly alike.

When the Earth's crust was being formed and was still in a molten state, gas pockets and cavities formed in relatively low temperature, volatile magma. After the magma cooled and hardened into rock, the hollow cavities became filled with high-temperature, mineral-rich fluids. Layers of agate deposited from the fluids began to form, usually following the shape of the cavity.