This is a rectilinear fragment of a statue with three worked surfaces. It may be part of a back pillar. The stone is grayish-green greywacke.
From Nubia (Sudan), Kerma, K III 4(1). 1914: Excavated by the Harvard University–Boston Museum of Fine Arts Expedition; assigned to the MFA by the government of Sudan.
Harvard University—Boston Museum of Fine Arts Expedition