This is a light weight lunar hammer designed to chip a sample of rock off a larger rock or to drive core tubes into the lunar soil. When attached to an extension handle, the hammer could also be used to dig surface furrows. Hammers of this style were used on Apollo 11 and 12.
This particular hammer was used for training. It was transferred to the Smithsonian in April 1971.
This object is on display in Destination Moon at the National Air and Space Museum in Washington, DC.