Rhomboid shaped cosmetic palette carved from mudstone (also known as greywacke or slate). Objects like this were used with a pebble to grind minerals such as malachite to make eyepaint.
Professor Percy Newberry's record card indicated the palette was excavated in Petrie's Predynastic cemetery U near the modern village of Hiw (How/Hu), but the grave number is not recorded. The palette is similar in shape to those illustrated in Petrie's 'Disopolis Parva' pl. XII, nos. 44-6.