Creationist Robert Gentry has argued that ring-shaped discoloration haloes in primordial granite rocks are the result of damage from alpha-particle emission by radioactive isotopes of the element polonium (Po). Since radiogenic polonium has a very short half-life (usually measured in fractions of a second), Gentry argues that, if granite takes thousands to millions of years to form as mainstream geology believes, any polonium originally present would have decayed away long before the granite could have formed and could not have produced these haloes. Therefore, he feels that their existence is evidence for an instantaneous and recent creation of these granite rocks, and by extension the Earth. The following articles point out the flaws in Gentry's argument.

"Polonium Haloes" Refuted

Professional geologist Tom Bailleul takes a second look at Gentry's claimed polonium haloes, arguing that there is no good evidence they are the result of polonium decay as opposed to any other radioactive isotope, or even that they are caused by radioactivity at all. Gentry is taken to task for selective use of evidence, faulty experiment design, mistakes in geology and physics, and unscientific principles of investigation and argument style.

Evolution's Tiny Violences: The Po-Halo Mystery

Amateur scientist John Brawley investigated Gentry's claims directly by studying local rock samples, and concluded that there is no good evidence that these "polonium" haloes are actually produced by polonium at all, as opposed to longer-lived radionuclides such as radon or uranium.