One case described at great length in UFO literature (Lorenzen, 1962) emphasizes metal fragments that purportedly fell to earth at Ubatuba, Sao Paulo, Brazil from an exploding extra-terrestrial vehicle. The metal was alleged to be of such extreme purity that it could not have been produced by earthly technology. For that reason, this particular material has been widely acclaimed as a fragment of an exploded flying disc. Descriptions of the material's origin and analyses occupy 46 pages of the Lorenzen book and the material is referred to in a high percentage of UFO writings. These fragments of magnesium metal -- undoubtedly the most famous bits of physical evidence in UFO lore -- were generously loaned to the Colorado project by Jim and Coral Lorenzen of APRO for analysis. 

The story which associated these fragments with an UFO is even more tenuous than most UFO reports, since the observers could never be identified or contacted because of the illegibility of the signature on the letter which described the event. According to the account by Olavo T. Fontes, M.D., a Rio de Janeiro society columnist wrote, under the heading, "A Fragment From a Flying Disc" 
 
 

Following the appearance of this account, the claim was published that analyses of the fragments, performed by a Brazilian government agency and others, showed the fragments to be magnesium of a purity unattainable by production and purification techniques known to man at that time. If this proved to be true, the origin of the fragments would be puzzling indeed. If it could then be established that the fragments had actually been part of a flying vehicle, that vehicle could then be assumed to have been manufactured by a culture unknown to man. 

The first step in checking this claim was independent analysis of the magnesium fragments, and comparison of their purity with commercially produced pure magnesium. A comparison sample of triply sublimed magnesium, similar to samples which the Dow Chemical Company has supplied on request for at least 25 years, was acquired from Dr. R. S. Busk, Research Director of the Dow Metal Products Dept., Midland, Mich. Since it was assumed that extremely small quantities of impurities would need to be measured, neutron-activation analysis was selected as the analytical method. The samples were 
taken to the National Office Laboratory, Alcohol and Tobacco Tax Division, Bureau of Internal Revenue, at which the personnel had no special interest in the UFO question. The neutron irradiation and gamma spectrometry were personally observed by this writer. The analysis was performed by Mr. Maynard J. Pro, Assistant Chief, Research and Methods Evaluation, and his associates. Original irradiation data and gamma-spectrometer read-out tapes are preserved in 
project files. 

The material irradiated was a chip broken from the main fragment. It was immersed in HCl to remove surface contamination. After washing, the sample presented a bright, shiny, metallic surface. The absence of chlorine emissions in the gamma-ray spectra after neutron activation showed both that washing had been thorough and that chlorine was not present in the sample itself. The concentrations of eight impurity elements were measured. Results are given in parts per million parts of sample, with limits of error estimated on the basis of greatest conceivable error. The "UFO fragment" compared with the Dow material as follows: 
 
 

Mn, Al, Zn, Hg, and Cr values were obtained from direct gamma spectrometry and half-life measurement; Cu, Ba, and Sr values were obtained by gamma spectrometry after radiochemical separation of the elements. In the latter cases, known standard samples of these elements were irradiated and analyzed concurrently with the specimen. Results, within the limits of error indicated, should be quite dependable. Since spectrographic analyses routinely performed on purified magnesium show no other elements present at concentrations of more than a few parts per million, the analytical results presented above show that the claimed UFO fragment is not nearly as pure as magnesium produced by known earthly technology prior to 1957, the year of the UFO report. 

The neutron activation analysis also was utilized as a means of checking the magnesium isotopic content. The suggestion had been made (Jueneman, 1968) that the fragment might be composed of pure Mg26, and therefore the magnesium isotopic content of this fragment should be determined. The suggestion was based on assumed qualities of such a pure isotope and on a density figure of 1.866 gm/cc, which had been reported for the center of one of the magnesium pieces "as determined in replicate using a Jolly balance" (Lorenzen, 1962). It is interesting that this figure was chosen over the density figure of 1.7513 gm/cc, also reported in the Lorenzen book, which was determined at a US Atomic Energy Commission laboratory by creating a liquid mixture in which the fragment would neither float nor sink, and measuring the density of the liquid. The quantity of Mg27 isotope produced by neutron activation [Mg26 (n, gamma) Mg27, as determined by gamma spectrometry after activation, showed that the Brazil sample did not differ significantly in Mg26 isotope content from other magnesium 
samples. 

Although the Brazil fragment proved not to be pure, as claimed, the possibility remained that the material was unique. The high content of Sr was particularly interesting, since Sr is not an expected impurity in magnesium made by usual production methods, and Dr. Busk knew of no one who intentionally added strontium to commercial magnesium. The sample was, therefore, subjected also to a metallographic and microprobe analysis at the magnesium Metallurgical Laboratory of the Dow Chemical Company, through the cooperation of Dr. Busk and Dr. D. R. Beaman. Again, all work was monitored by this writer. Microprobe analysis confirmed the presence of strontium and showed it to be uniformly distributed in the sample (see Case 4). In all probability, the strontium was added intentionally during manufacture of the material from which the sample came. Metallographic examinations show large, elongated magnesium grains, indicating that the metal had not been worked after solidification from the liquid or vapor state. It therefore seems doubtful that this sample had been a part of a fabricated metal object. 

A check of Dow Metallurgical Laboratory records revealed that, over the years, this laboratory made experimental hatches of Mg alloy containing from 0.1% - 40% Sr. As early as 25 March 1940, it produced a 700 gm. batch of Mg containing 
nominally the same concentration of Sr as was contained in the Ubatuba sample. 

Since only a few grams of the Ubatuba magnesium are known to exist, and these could have been produced by common earthly technology known prior to 1957, the existence and composition of these samples themselves reveal no information about the samples' origin. The claim of unusual purity of the magnesium fragments has been disproved. The fragments do not show unique or unearthly composition, and therefore they cannot be used as valid evidence of the extra-terrestrial origin of a vehicle of which they are claimed to have been a part.