All other isotopes of aluminium are radioactive. By far the most secure of those is 26Al, having a 50 %-lifetime of 717,000 decades: although it absolutely was current together with stable 27Al in the interstellar medium from which the Solar Procedure fashioned (believe to have already been produced by stellar nucleosynthesis https://aluminium-greenhouse45566.blogocial.com/5-simple-statements-about-aluminium-greenhouse-explained-73194250