Orpiment is a bright yellow mineral composed of arsenic sulfide, with the chemical formula As2S3. It is often found in hydrothermal veins and can occur alongside other minerals like realgar. Historically, orpiment has been used as a pigment in art and cosmetics due to its vibrant color. Despite its striking appearance, orpiment is toxic because it contains arsenic. This toxicity has led to its decline in use for artistic purposes. Today, orpiment is primarily of interest to mineral collectors and researchers studying arsenic compounds and their environmental impacts.