Aktashite is a rare arsenic sulfosalt mineral with formula Cu<sub>6</sub>Hg<sub>3</sub>As<sub>4</sub>S<sub>12</sub>. It is a copper mercury-bearing sulfosalt and is the only sulfosalt mineral with essential Cu and Hg yet known. It is of hydrothermal origin. It was published without approval of the IMA-CNMNC, but recognized as valid species by the IMA-CNMNC Sulfosalts Subcommittee (2008).