Hola amigos,
Thank you Somehiker for outlining the important areas. It is really hard to judge anything from photos, and you have examined them up close (in person) which makes a world of difference. Tool marks, like from chisels etc are tough to see from a photo and would be key to proving a carving IS a carving and not a natural formation.
Perhaps we are not seeing the details because when we read "Aztec carving" we expect to see something like this
...but is it realistic to expect the Aztecs to have made elaborate carvings so far from their homelands, especially if they were trying to HIDE something?
Anyway thanks again Somehiker for sharing the photos and everyone for their opinions. The mystery of what happened to the vast gold and silver treasure seen and handled by Cortez before the La Noche Triste (retreat from Tenochtitlan) has puzzled folks for nearly 400 years, someday perhaps we will know the truth.
Roy ~ Oroblanco