Gypsum

Gypsum was a white mineral substance used in the creation of plaster and alabaster.

Description
Gypsum was a relatively soft mineral. A test could be used to determine its authenticity – gypsum could not be scratched by a fingernail but rather by using a copper or bronze coin. Satin spar was a type of gypsum mineral, also known as feather gypsum, that was used in gem-cutting.

Usage
The city of Ankhapur in the Land of the Lions had walls that looked to be made of white gypsum, though tarnished in appearance.

The Mulhorandi deity Geb had his temples constructed to be living caverns adorned with mineral formations, including gypsum flowers.

Availability
Gypsum was found within the rocks of the great desert of Anauroch in North Faerûn. Deposits of the substance were broken off and harvested by the Bedine humans along with the less valuable gypsum dust.

Aurora's Whole Realms Catalogue sold gypsum in eight-ounce bags for a single silver piece, available from the Wizard's Laboratory of the catalogue.

Crystal flowers of the Underdark were beautiful natural mineral formations of halite, gypsum, and other substances. They were valued by the sentient inhabitants of the Underdark for their beauty.

The scales of radiant dragons consisted of glistening mica and gypsum.