This is a slice of an Agate geode which has been dyed to enhance the unique natural patterning. Due to the fact that each of these pieces are completely unique they may differ slightly from the examples pictured.
Agate is one of the most common materials used in the art of hard-stone carving, and has been recovered at a number of ancient sites, indicating its widespread use in the ancient world.
Agate is a crypto-crystalline variety of silica, chiefly chalcedony, characterized by its fineness of grain and brightness of color. Although agates may be found in various kinds of rock, they are classically associated with volcanic rocks and can be common in certain metamorphic rocks.