Orichalcum

Before there was mithril, there was orichalcum.
This magical metal is neither steel nor bronze, but has an appearance somewhere between the two, like the surface of molten pewter just as the heat turns the colour. It is slightly lighter than bronze or steel, but nowhere near as light as mithril.
No man living today knows the secret source of orichalcum, it is unknown if it is an alloy, or a pure metal extracted from ore. When worked, it has to be melted, then cast and work-hardened like bronze by someone with the specialist tools and knowledge required. Also like bronze, when broken it bends long before snapping (someone with a bronze crafting skill can bend an item that is just bent back into shape, but it’s magic damping properties mean that an ordinary Mending spell is unlikely to work.
A weapon made of orichalcum is automatically masterwork, and has an additional cost of +4000 for a weapon or +100 for a piece of ammunition. It is generally not made into shields or armour.
There is one peculiarity; the elves of Sidhiara have orichalcum coins they call Stars. They are hugely ornate, looking as if they have been grown, made of lace or spiderwebs. Although very valuable and sought after, they are rarely seen outside Sidhiara, and despite being pure orichalcum, it is the artistry rather than the (quite low) weight of metal which contributes so much to their value.

In terms of its powers (and with reference to D&D 3.5), it has four main properties;

• It has the impact of adamantine on crystal, stone, wood, copper and bronze objects. Unlike adamantine, it confers no damage reduction if incorporated into armour, nor does it have special properties against iron or steel.
• A weapon made of orichalcum, if enchanted to at least +1, gains the power of ghost touch automatically without costing the normal +1 bonus.
• When made into a form which can be used to restrain an arcane spellcaster’s hands or wrists, it has the effect of damping their magical abilities significantly, fogging their minds and forcing a concentration check at DC30 plus spell level. Of course, if the spellcaster can slip free of his or her bonds, this is not a problem for them ! 
• It should be noted that ordinary smiths don’t have the tools or knowledge to work orichalcum, and for a player to learn it as a crafting skill requires training by one of the very, very few people left alive with this knowledge.
• Finally, there are certain very ancient (and often powerful) creatures and beings whose damage resistance is only overcome with weapons made of this metal.