Cold Iron

An ore that is found commonly in various mountain ranges and caverns, cold iron is a dark grey metal that is similar to typical iron with a sheen in varying shades of blue. It can be easily confused with typical iron by the untrained, and commonly is. A moderately skilled blacksmith is required in order to bring out its inherent properties (see Properties).

Properties

Physical & Chemical Properties

Armour: While wearing armour forged with cold iron, fey creatures have disadvantage on melee attacks against you.

Weapon: When you hit a fey with a cold iron weapon, you can roll the damage again and use either result. The weapons will also overcome resistance to non-magical bludgeoning, piercing or slashing damage against fey.

History & Usage

History

Deep Gnomes were the first to uncover the usefulness of cold iron. Rendering items of slightly superior protection when compared to typical iron, they found it offered them a number of additional benefits when they were forced to face certain evil races of fey native to the Underdark. They actively began seeking out and reserving it for weapons, armor and certain magical items.
Other advanced races of the Underdark soon learned of its properties, and began to employ it in the same fashion, sometimes making composite metals to offer additional benefits.
First known use of cold iron on the surface was by the Dwarves of the Ingetium, which they learned of by means of an adventuring party wandering deep into the Underdark in order to search out rare and precious metals, gems and other materials to be used in their works.

Discovery

First known to be commonly used by Deep Gnomes, then branching out amongst the other advanced races of the Underdark, before finally being made known to the surface-dwelling races of Ostradin.
It is likely that it had been used for centuries before the recognition of its inherent properties by being mistaken for typical iron and may have been forged into various everyday items and tools before being recognized as a completely different metal.
It could also explain the misconception that an  "iron" horseshoe mounted over your door will prevent the entry of fey, which is a common belief among some simple folk.

Everyday use

It is commonly used in many different types of weapons and armor, but can often be found in mundane items due to the aforementioned confusion.

Type

Metal

Value

150 GP per Unit

Rarity

Common

Color

Grey to dark grey, with a sheen of varying shades of blue. Darker hues indicate higher quality.