Nune

Nune was the common name for staurolite (sometimes called "cross stone" or "fairy stone") in the Realms.

Description
These ornamental stones were translucent brown or nearly clear and occurred in small cross-shaped crystals up to one inch (two and a half centimeters) across either arm. These were commonly polished to a smooth sheen and pierced to be worn as pendants or linked as bracelets. On Toril, the cross was used as an ornament and not as a holy symbol. A typical stone had a base value of 10 gp.

Powers
Nune stone powder was an essential ingredient of the ink used to scribe dispel magic scrolls and it was added to the immersion treatment when preparing to enchant a wand of negation.