Arsenic: The "King of Poisons"

Few things are saddled with darker connotations than arsenic. Used throughout much of history as a human poison, arsenic has become inexorably linked with death.

- By Steve Voynick

From medieval times through the mid 1800s, members of Europe's ruling classes frequently used arsenic to dispose of one another. Fittingly, arsenic became known as both the "king of poisons" and, wryly, the "poison of kings." In France, arsenic was called "inheritance powder," alluding to its frequent use by impatient heirs to accelerate the demise of family members.

But there is more to arsenic than a sinister image. Specimens of arsenic's two most familiar minerals, realgar and orpiment, are widely collected for their crystalline beauty and bright colors. In powdered form, these same minerals have been used in medicine and as pigments in the celebrated paintings of many European masters.

THE METAL & ITS MINERALS

Elemental arsenic is dark-gray, brittle, and a poor conductor of electricity. As a semimetal, it exhibits both metallic and nonmetallic properties. Ranking 55th in crustal abundance, it is about as common as tin. Although occasionally found free in nature, most arsenic is a component of more than 250 minerals, the most abundant being arsenopyrite (iron arsenic sulfide), which forms opaque, prismatic crystals with a steelgray color and metallic luster.

Next in abundance are red realgar and yellow-orange orpiment. Both these arsenic sulfides crystallize in the monoclinic system; occur in close association, and share similar properties.

MEDICINE AND THE ARTS