Amber

Amber was not a mineral, but this fossilized tree resin was graded as a fancy stone by civilized peoples, and beads of almost any quality were traded as currency among the northern barbarians.

Description
Amber was yellow to gold to orange in hue, and very soft and brittle. It was easily worked into strings of beads, but larger pieces were usually tumbled into smooth stones or polished and cut cabochon. Specimens that contained other fossils, like plants and insects, were priced four to five times higher than the base value. A typical clear specimen had a base value of 100 gp.

Powers

 * Amber could be used as a material component for most spells that dealt with electrical discharge, from as small as shocking grasp to as powerful as chain lightning. It was also used to make the ink for inscribing such spells.
 * The Banite spell mystic lash used amber as a material component.
 * Casting the Tormish spell bolt of glory required the use of a bronze-banded amber rod.
 * Giant versions of insects and other vermin could be magically placed into a gem-quality amber to make an amber amulet of vermin.
 * A staff of eyes was tipped with a large piece of amber.
 * A specimen worth at least 500 gp was required as a focus for casting Simbul's spell matrix.
 * The stone walk spell required a paste made from amber and ruby dust to treat the areas where the spell would operate.
 * Powdered amber was used as a material component when creating a sepia snake sigil.

Rumors & Legends
Amber was believed to bring good luck in avoiding disease and plague, but this folklore was not based on fact.

Trivia

 * Amber gems were considered sacred to a number of deities, including Baervan Wildwanderer, Erevan Ilesere, Horus-Re, Lolth (with an encased spider), Rillifane Rallathil, Sheela Peryroyl (with an encased plant), Talona, and Yondalla. It was appropriate to consecrate or sacrifice amber to these deities, or a follower might find one as a boon or an omen.
 * The church of Talona believed that finding a single piece of amber was a sign of the goddess's favor, but if it shattered when touched, then it meant death by disease in the near future.
 * In the church of Torm, deep amber was the color (for robes or dyed armor) worn by priests with the medium-low rank of Warden.