These magnificent agate bookends are designed to keep your books upright while being a decorative addition to any home. The bookends are cut and shaped from natural agate geodes mined in Brazil. The exposed display sides of the bookends are polished while their back retains their natural outer rough crust of the geode. The color of the bookends is not their natural color. The bookends are dyed black so they may accommodate a variety of decorative themes for your home. Agate is a cryptocrystalline variety of silica, mainly 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.