Pair of Oaxacan Negra CupsA pair of cups made from black Coyotepec clay made in San Marcos Tlapazola. Enjoy your favorite fresh beverage in it with confidence. Black clay can hold liquids, no problem, as it has been doing for many centuries. San Bartolo Coyotepec is one of the most recognized pottery communities in Oaxaca, Mexico. It's known for its use of their attractive black clay, often times called Barro Negro. The metallic color of this clay is an indicator that it has