St. Juan Diego's tilma, bearing the miraculous image of Our Lady of Guadalupe, has been on display in Mexico for nearly 500 years, but it has not shown any signs of decay.
This reality has stumped many scientists, as the tilma was made of a material that should have decayed only a few short years after it was put on display.
Dr. Aldofo Orozco explained the situation at the International Marian Congress on Our Lady of Guadalupe in 2009, as recorded by Catholic News Agency.
All the cloths similar to the Tilma that have been placed in the salty and humid environment around the Basilica have lasted no more than ten years ... the original Tilma was exposed for approximately 116 years without any kind of protection, receiving all the infrared and ultraviolet radiation from the tens of thousands of candles near it and exposed to the humid and salty air around the shrine.
Furthermore, the tilma has endured all sorts of mistreatment, such as the accidental spilling of a 50% nitric acid solvent in 1785. The tilma was unharmed by the incident.
The tilma even survived a bombing of the basilica in 1921. Everything around the tilma was badly damaged, but not the tilma.
Dr. Orozco said that the preservation of the tilma was simply "beyond any scientific explanation.”