This is a 'mano', handheld grinding stone used with a metate for grinding. It is made from volcanic stone (basalt), which is the traditional material because it is extremely hard and slightly abrasive.  This is used for grinding corn, chiles, spices, cacao, or seeds on a metate.  We also sell metates, just search the word 'Metate'.  Beautiful natural wear and texture from use.  A wonderful piece of Mexican culinary history that also makes a unique rustic decor accent.  Please understand that these are old and will sometimes, have nicks, chips, etc...all minor and nothing that jeopardizes its use.  Measurement approximately 10-11 x 2-2.5 inches.