Calomel is a hard white ore that is most often found and quarried in Argonnessen, at great expense and danger. Calomel was famously utilized by the famous adventurer Arthul Vernuthan prior to his single combat against the power-mad red dragon Xarkapastarthan. Secretly mined, refined, and forged into a blade of slender gray death, the ore’s special attributes carried Arthul to victory, but his defeat of Xarkapastarthan embittered other dragons of the region, who decried Arthul as an opponent of the draconic Prophecy itself. Presumably Arthul was slain, and his blade lost. However, knowledge of calomel, where to mine it, and how to refi ne it still persists.
Raw calomel ore is distinctive in its whiteness. It can be almost translucent, and is lustrous in bright light. It is always found adjacent to subterranean springs. When forged in the appropriate secret fashion, the resultant metal cools to a consistency and ductility like that of a standard steel alloy. Though any item can be crafted from it, calomel’s particular qualities make it most suitable for weapons.
A weapon forged from calomel is pale gray, almost translucent, and water droplets constantly condense on the naked item. A calomel weapon overcomes damage reduction of creatures with the fi re subtype as if it were a magic weapon, even if it does not have an enhancement bonus. For example, a mundane calomel blade wielded against a mature adult red dragon (fire subtype) would overcome that creature’s damage reduction 10/magic as if it were a magic weapon.
Weapons made of calomel cost twice as much as their normal counterparts. For example, a longsword made of calomel would cost 30 gp. Items without metal parts cannot be made from calomel (so that an arrow could be made of calomel, but a quarterstaff could not). A double weapon with only one half made of calomel increases its cost by 50%. For example, a two-bladed sword with one blade of calomel and the other of steel would cost 150 gp. Calomel has hardness 10 and 30 hit points per inch of thickness.
Source: Magic of Eberron