As • Atomic number 33
Arsenic
Arsenic is a naturally occurring metalloid with the chemical symbol As. The stable grey form is brittle and has a metallic appearance. Arsenic is usually bound in sulfide minerals, especially arsenopyrite, and often occurs together with copper, lead, gold and other metals.
High-purity arsenic is important for compound semiconductors such as gallium arsenide. Arsenic compounds have also been used in glassmaking, metal alloys and, historically, pesticides and wood preservatives. Many older uses are now strictly restricted.
Arsenic is commonly obtained as a by-product during the treatment of copper, lead and gold ores. Processing must capture arsenic-bearing dust and gases and convert them into stable forms suitable for controlled storage or further use.
Arsenic and many arsenic compounds are highly toxic. Production, sampling, transport and disposal therefore require closed systems, effective extraction, strict hygiene and compliance with hazardous-substance regulations.
The technical assessment of a material always depends on purity, chemical form, particle size, packaging and intended use.