Orichalcum is a magical metal that is very rare, and only found in large concentrations. It is virtually unheard of to find small quantities of Orichalcum rather than large veins of it.
It is also never found in ore form, it's all native, and generally formed into strange, almost intelligent shapes that often indicate towards another deposit of the stuff. Most speculate that it is of some magical or divine origin.
Its chief quality is that it is impossible - actually impossible - to deform the metal so long as it is in contact with living flesh or blood. No force yet found has been able to compress it under these conditions. When not in contact with living matter, it could easily be mistaken for gold.
It also produces magical energy in and of itself, much as the Orredin do, furthering its great value, and making it ideal for self-powering enchanted weapons.
Its magical uses as a conduit for sorcery, in weapons, and for more arcane alchemical uses, have made it highly sought after, and as the Orredin have shown, people are quite willing to stripmine entire countries to acquire the stuff.
A great many Orichalcum weapons and armors are actually steel, laced with, edged by, or leafed with Orichalcum. Since Orichalcum is about as heavy as gold, this makes the weapon more wieldy, and generally it's about as unbreakable as it needs to be then.
There are problems with this. For one thing, Orichalcum shares gold's melting point, making it extremely difficult to forge alongside steel. There are a lot of ways around this, like designing the steel framework and then pouring or working orichalcum into it. It also makes repairs really hard to conduct on the steel, since any attempt to heat the thing up would invariably melt the orichalcum out of it unless someone was holding it with their bare hands.
Pieces of Orichalcum can transfer the life-current through each other, but this does not bond separate pieces of them together. The current transfers through, say, links in a chain, but the chain itself remains flexible. Of course, when rattling and whipping around, one link might be separated from the others by the span of a millimeter for an instant, and that IS enough time for immense forces to assert themselves further down the line.
If you dropped a brick of it onto a knight, it would immediately become rigid upon contact his suit (and thus him.)
The uses are endless! Much of the flying city of Helion is held together by incredibly thin wires of Orichalcum, all leading to some central nexus of the city, where something living is kept in contact with it at all times.