And on a total tangent, this fact played a part in worldbuilding done by the author L. E. Modesitt, Jr.
> When I initially decided to write The Magic of Recluce in the late 1980s, I'd been writing science fiction exclusively... I conveyed a certain dismay about the lack of concern about economic, political, and technological infrastructures in various fantasies then being written and published in the field...
> I faced the very real problem of creating a magic system that was logical... Most fantasy epics have magic systems. Unfortunately, many of them, particularly those designed by beginning authors, aren't well thought out, or they're lifted whole from either traditional folklore or gaming systems and may not exactly apply to what the author has in mind.
> I began by thinking about some of the features and tropes of traditional fantasy. One aspect of both legend and folklore that stuck out was the use of "cold iron" to break faerie magic, even to burn the creatures of faerie, or to stand against sorcery. Why iron? Why not gold or silver or copper? Not surprisingly, I didn't find any answers in traditional folklore or even contemporary fantasy. Oh, there were more than a few examples, but no real explanations except the traditional ones along the lines of "that's just the way it works."
> For some reason, my mind went back to astronomy and astrophysics and the role that nuclear fusion has in creating a nova... Each of these fusion reactions creates a heavier element and releases energy... The proton-proton reaction that produces iron, however, is different, because it is an endothermic reaction...
> At the same time, the fact that metals such as copper or silver conducted heat and electrical energy suggested that they were certainly less than ideal for containing electrical energy. Gold and lead, while far heavier than iron, do not have iron's strength, and other metals are too rare and too hard to work, particularly in a low-tech society.
> At this point, I had a starting point for my magic system. I couldn't say exactly what spurred this revelation, but to me it certainly made sense. Iron can absorb a great amount of heat. If you don't think so, stand on an iron plate barefoot in the blazing sun or in the chill of winter. Heat is a form of energy. In fantasy, magic is a form of energy. Therefore, iron can absorb magic and, by doing so, bind it.
> When I initially decided to write The Magic of Recluce in the late 1980s, I'd been writing science fiction exclusively... I conveyed a certain dismay about the lack of concern about economic, political, and technological infrastructures in various fantasies then being written and published in the field...
> I faced the very real problem of creating a magic system that was logical... Most fantasy epics have magic systems. Unfortunately, many of them, particularly those designed by beginning authors, aren't well thought out, or they're lifted whole from either traditional folklore or gaming systems and may not exactly apply to what the author has in mind.
> I began by thinking about some of the features and tropes of traditional fantasy. One aspect of both legend and folklore that stuck out was the use of "cold iron" to break faerie magic, even to burn the creatures of faerie, or to stand against sorcery. Why iron? Why not gold or silver or copper? Not surprisingly, I didn't find any answers in traditional folklore or even contemporary fantasy. Oh, there were more than a few examples, but no real explanations except the traditional ones along the lines of "that's just the way it works."
> For some reason, my mind went back to astronomy and astrophysics and the role that nuclear fusion has in creating a nova... Each of these fusion reactions creates a heavier element and releases energy... The proton-proton reaction that produces iron, however, is different, because it is an endothermic reaction...
> At the same time, the fact that metals such as copper or silver conducted heat and electrical energy suggested that they were certainly less than ideal for containing electrical energy. Gold and lead, while far heavier than iron, do not have iron's strength, and other metals are too rare and too hard to work, particularly in a low-tech society.
> At this point, I had a starting point for my magic system. I couldn't say exactly what spurred this revelation, but to me it certainly made sense. Iron can absorb a great amount of heat. If you don't think so, stand on an iron plate barefoot in the blazing sun or in the chill of winter. Heat is a form of energy. In fantasy, magic is a form of energy. Therefore, iron can absorb magic and, by doing so, bind it.
https://www.lemodesittjr.com/the-books/saga-recluce/recluce-...