Basic Information
Iron is one of the most common elements on earth, but interestingly it occurs almost exclusively as various rocky ores that requires significant processing to extract the metal content. Post extraction, this is known as pig iron, and it can in turn be used to make steel. The technology by which iron is refined from its ores is an important limiting factor in the materials which can be made from it - early iron smelters, known as bloomeries, produced relatively small lumps of solid iron which needed extensive working to remove mineral impurities. Items of significant size would need to be assembled from multiple blooms which impeded the creation of large metal pieces such as iron or steel plate armour, and the inability to melt iron ruled out any casting based fabrications at all. Later developments, such as the blast furnace produced large quantities of liquid iron, which could be cast into pigs (as above) or directly into required shapes.
Telluric iron is naturally-occurring iron in its pure (or nearly so) metallic state. This is extremely rare on earth, with the only major deposits worldwide occurring in Greenland.
Cold Iron, as called for in folklore, fantasy and Hollywood is a subset of iron, that is sometimes mentioned as a potent vulnerability of fairies or other mythological creatures, and can be used as "depleted phlebotinum shells". But what exactly cold iron is technically remains a little sketchy scientifically. See the Cold Iron page for more information and ideas.
Meteoric Iron is iron that fell to earth from the heavens. It's usually in the form of an iron and nickel alloy such as kamacite or taenite, but is sometimes found as pure metallic iron similar to telluric iron except extraterrestrial in nature. Such sky metal has been recognized as special for thousands of years, and was often used for custom gear or gifts for Pharaohs and Emperors.
Bog Iron: While we usually picture or expect Iron to be dug out of the earth by a miner, sometimes it's pulled out of the muck of a peat bog by a bog-iron hunter instead.
Early iron weapons and armour appear to have been substantially inferior to those of bronze (even discounting the inability of early blacksmiths to cast iron or create large pieces without welding) but, due to the relative prevalence of workable iron ores, they could be made a lot cheaper: an iron-using culture could overwhelm a bronze-using one by equipping more men with slightly inferior equipment.
Sources
Game and Story Use
- The quality, source, and craftsmanship of iron ore and iron products can have a big impact on the balance of power in a setting. If one side has mastered the riddle of steel but it's national enemies only have bronze or low-grade iron, that could end up in a very lopsided conflict.
- The bronze vs. iron dynamic could make for a good "heroes vs. mooks" atmosphere with a small number of highly skilled men armed and clad in bronze fighting larger numbers of iron armed grunts.
- Cold Iron, Telluric Iron, and Meteoric Iron are all good options for required components for magic item creation, or possible depleted phlebotinum shells options.
- One of the setting options for Night's Black Agents is "telluric vampires" who have a special link to the energies from deep within the earth. Such creatures are likely to be either vulnerable to, empowered by, or possibly armed with telluric iron weapons. Or they might be vulnerable to meteoric iron because it comes from somewhere beyond the earth. Details and options can be found in the Dracula Dossier Director's Handbook, and might inspire something similar in your own setting.
- See the Cold Iron page for more information and ideas about iron.
- Certain supernatural creatures - such as hags - are known to have iron teeth and/or claws. Presumably such iron might have … interesting … properties if taken and forged into something more useful to humanity.