Moonstone

Moonstone was an opaque white form of feldspar found in the Realms.

Description
Moonstones took on a milky bluish sheen when polished and were usually cut cabochon for jewelry and ornamentation. A typical specimen had a base value of 50 gp.

Powers
The sorcerer Pelathyon Hawkryn of Impiltur (whose family owned lucrative moonstone mines) was a proponent of what he called "moonstone magic"&mdash;the ability of moonstone dust to substitute for other non-organic components of spells, specifically various abjuration spells, such as walls and barriers, and certain evocation spells where powdered moonstone provided storage of magical energy and the quick release of that energy in a new direction. Careful research was required to determine the optimal amount of moonstone required for each substitution.

Rumors and Legends
Legends about lycanthropes said that the mere sight of a moonstone would cause a were-creature to shift to animal form. Though this was not true (in fact, many lycanthropes wore moonstones in jewelry), magic items that affected lycanthropes or warded against lycanthropy often used moonstones in their creation and ornamentation. This may have been related to, or an outgrowth of, the fact that moonstones were considered sacred to Selûne by her followers, many of whom hunted down evil lycanthropes.

If moonstones appeared in a dream, it was considered a warning of danger.

Appearances

 * Icewind Dale