This geologist's tool is designed in the shape of a pencil with pocket clip, a small magnet at the tip, and a spring wire clip at the center. When the 'pencil' is held by this wire clip, it pivots on the center holder and the magnet at the tip is attracted to magnetic minerals present in a rock specimen that is brought into its proximity.
Note: Although this tool is named a 'pencil', it's actually not a pencil nor a writing instrument. The name is solely derived from the shape and look of the tool.