The common ones are iron, nickel, cobalt and most of their alloys, some compounds of rare earth metals, and a few naturally-occurring minerals such as lodestone.
According to his biographer, he used to celebrate with such living piety that he was like a lodestone, attracting the faithful to the altar where he offered the sacrifice.
In addition to the magnetite which forms both massive lodestone and crystals, the complex is strewn with odd and rare minerals, and is the type locality for five mineral species.
He considered that gravity was a magnetic force and noted that this mutual force increased with the size or amount of lodestone and attracted iron objects.