Arsenic is a gray or yellow crystalline that often looks like a jagged rock when it is in its natural state. It is typically somewhat shiny, resembling silver.
Arsenic is also often found in chemical compounds, though these vary in appearance. In very rare cases, black arsenic can be found. Arsenic is often combined with other metals to make strong metal alloys. When it is burned or combined with oxygen or hydrogen, arsenic makes a deadly poison that has been used in chemical weapons. The most prominent chemical weapon to use arsenic was lewisite, which was a blistering agent and a lung irritant.