Life magazine ran an article in 1952 titled "Have We Visitors from Space?" which mentioned Lincoln LaPaz and the "green fireballs". They did indeed give off some kind of copper residue, but they were not meteorites, ball lightning or anything else along those lines:
"The popular Southwest belief that a strange meteor shower was underway has been blasted by Dr. Lincoln LaPaz, mathematician, astronomer and director of the Institute of Meteoritics at the University of New Mexico. He points out that normal fireballs do not appear green, they fall in the trajectory forced on them by gravity, are generally noisy as a freight train, and leave meteorites where they hit. The green New Mexican species does none of these things. Neither do the green fireballs appear to be electrostatic phenomena – they move too regularly and too fast
If the fireballs are the product of a U.S. weapons project, as some Southwesterners believe, it is a very secret one indeed: the Atomic Energy Commission and every other government agency connected with weapons development has denied to LIFE any responsibility for the fireballs.
Could they be self-destroying Russian reconnaissance devices? Not likely. While the U.S. believes the Russians have an intercontinental guided missile, there is no intelligence that indicates they have developed silent power plants or objects capable of moving nearly as fast as meteors (12 miles a second). Yet – for whatever it may be worth – the only reports of green fireballs prior to 1948 came from the Baltic area.
If the fireballs do not respond to gravity, they could only be explained as lighter-than-air craft or electrical phenomena – but they have characteristics which rule these out. Therefore they must be propelled. If propelled and not natural phenomena, they must be artificial. The extreme greenness of the fireballs has impressed most witnesses. When asked to indicate the approximate color on a spectrum chart, most of them have touched the band at 5,200 angstroms, close to the green of burning copper. Copper is almost never found in meteorites; the friction of the air oxidizes it shortly after the meteor enters the upper atmosphere. However, a curious fact has been recorded by aerologists. Concentrations of copper particles are now present in the air of Arizona and New Mexico, particularly in "fireball areas." These were not encountered in air samples made before 1948."
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