Arsenic's atomic number is 33 and its symbol is As. Arsenic is usually found in combination with sulfur, as a pure crystal, or in volcanic ash. This metalloid has a dangerous-sounding name that is well deserved because of its toxicity. This high level of toxicity is why arsenic was commonly used in crop pesticides and wood preservatives to keep insects, bacteria, and fungi at bay. However, developed countries have phased out arsenic pesticides because of their harmful effects on food and the people that eat them. Another common use for arsenic is as an alloy with lead to create semiconductors in electronics. Although arsenic is toxic to many organisms, it is also an essential dietary element in rats, hamsters, goats, and chickens. Pure arsenic will slowly oxidize when exposed to the atmosphere. The arsenic in these cubes is pure arsenic encapsulated in a glass ampule to prevent oxidation. The glass ampule containing the sample is suspended in crystal clear Lucite acrylic.