Obdurium

From the foreign realm known as Oearth, Obdurium is a fantastically rare metal that is even harder than adamantine. Pale violet in colour, obdurium is the pinnacle of nonmagical metal strength. It is also nearly prohibitively expensive, building with it costs ten times as much as carving stone walls and sixty times what a normal wooden wall would cost to build.Expedition to the Ruins of Greyhawk by Jason Bulmahn, James Jacobs and Erik Mona.

Mechanical Effects

• Suits of armour made of Obdurium offer Damage Reduction 5/- to light armour, 7/- to medium armour, and 10/- to heavy armour, and are corrosion-resistant, at the cost of being substantially heavier (150%).
• Weapons made of Obdurium offer the keen property and are corrosion-resistant, at the cost of being substantially heavier (150%). Obdurium is too heavy to make effective arrows or bolts, and such projectiles suffer a -1 attack bonus. Sling shots carry this bonus due to unwieldly weight, but do 2d4 more damage due to it.
• Shields made of Obdurium have additional hitpoints and grant a +10 circumstance bonus against Disarm checks, at the cost of being substantially heavier (150%).

Items which do not carry a significantly metal component such as leather armour, hide armour, or whips, cannot be made of Obdurian.