File / ubatuba-1957
The Ubatuba Magnesium
The most famous “UFO sample” and a lesson in chain of custody
Fragments of very pure magnesium were said to come from an object that exploded above a beach. The samples passed through many analyses, including in government laboratories, but the story of their origin was never independently established.
Official position
Analyses showed high-purity magnesium, achievable by industrial methods known in the 1950s.
Alternative hypotheses
- Terrestrial industrial material of high purity — consistent with the analytical results.
- A hoax: no witness to the event was ever identified and no documentation of the sampling exists.
Why this is a model case — negatively
Ubatuba shows that laboratory analysis of material of unknown origin has no evidential value, however precise the analysis itself.
We can establish with great precision that a sample is magnesium of purity X. We cannot establish in any way that the sample came from an object that exploded above a beach — because there is no documented chain of custody from the site to the laboratory.
The same problem recurs exactly sixty years later with the celebrated magnesium-bismuth sample examined by AARO. The conclusion is identical, and it is one of the most important in the field: without a chain of custody there is no material evidence.
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