This is a flat roughly rectangular polished black stone implement. The ends are rounded. It is broken in three pieces and two are mended. There is a chip missing from one end. There are no details indicated.
From Giza: G 7652A, Room VI [Excav. date] April 29, 1929. Excavated by the Harvard University–Museum of Fine Arts Expedition; assigned to the MFA by the government of Egypt.
Harvard University—Boston Museum of Fine Arts Expedition