Mexican Black Clay Oaxacan Pottery & Figurines Potters and sculptors in Oaxaca, Mexico create a specific type of pottery call barro negro, "black mud". It is made in the area of San Bartolo De Coyotepec. The clay of this region has specific qualities. The polished smooth surface with intricate carvings and fine details combined with the rich black color make this pottery very distinguishable and uniquely Oaxacan. Each piece is handmade and baked in a fire of thick black smoke to produce the unique color. Oaxacan black clay vases and pots cannot hold water or food. They are purely decorative.