Ghost-like mounds of powder-like gold can be seen, forever waiting for transportation to the northern Mexican city of San Luis Potosi for refinement.

BBC: In Oaxaca, a community unchanged

Friday's warning also specifies dangers and advises against nonessential travel in parts of the states of Durango, Chihuahua, Coahuila, Jalisco, San Luis Potosi, Sinaloa, Sonora and Zacatecas.

CNN: U.S. broadens Mexico travel warning