Arsenic (as you probably already know) is infamous for its use as a poison. During the 19th century, arsenic’s frequent use as a means of offing one’s relatives earned it the name, “inheritance powder”. Element number 33 also formerly saw use in green pigments, rat poison, glass manufacturing, and in pesticides. Gradually, arsenic has been phased out of these applications. The compound gallium arsenide (GaAs), though, is still widely used as a semiconductor material in a wide variety of electronic devices.

Currently, my only samples for arsenic are mineral specimens.

Two small crystals of adamite (zinc arsenate hydroxide).

Shown above are two crystals of adamite (Zn₂AsO₄OH), mined in Mexico. As interesting as this sample is, though, it is overshadowed by my other arsenic mineral sample.

A sample containing stibnite (antimony sulfide), baryte (barium sulfate), realgar (arsenic sulfide), and native arsenic.

This interesting looking sample from Romania includes silver stibnite (Sb₂S₃) and clear baryte (BaSO₄). The arsenic content comes from the small crystals of red realgar (As₄S₄) and the black sprays of oxidized native arsenic. Photos don’t really do justice to how cool this sample looks in real life, and I consider it to be one of the most visually appealing samples in my collection.