The image shows a pair of onyx bookends. These are carved stone bookends, often made from onyx or alabaster marble, and are commonly found in mid-century modern or vintage styles.
Onyx is a type of chalcedony, which is a variety of quartz.
It is known for its parallel bands of color, which can be black, white, brown, or other hues.
Onyx is found in various regions around the world, including Brazil, Argentina, Mexico, and the United States.
The stone is often used for jewelry, carvings, and decorative objects due to its unique appearance.