Oaxacan barro negro ceramic vase with carvings featuring distinctive black clay, to include pedestal. Barro negro is a style of pottery unique to Oaxaca, Mexico and its practice dates back to pre-Columbian Mexico. As Oaxaca's most celebrated ceramic practice, it's easily identifiable by its unique designs, sheen, and above all, striking black color. Barro negro pottery is not colored, instead its distinctive black color is due to the unique clay found in the region.