Rusteen

Rusteen was the Realms name for microlite.

Description
Rusteen occurred in shades of brown from pale to dark reddish brown. They were small but very hard and could be cut into faceted gems and used to decorate swords, armor, shields, and horse tack. A typical specimen had a base value of 500 gp.

Powers
This precious stone could be used as a material component for forcecage and wall of force spells.