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Cinnabar (mercury sulphide - HgS) is the single most toxic mineral to handle on earth. It is the worldâs main source of mercury and has been mined since Neolithic times. However, when oxidized, this element will produce methyl mercury and dimethyl mercury, two toxic compounds that cause irreparable harm to the nervous systems of children. It is deadly in small concentrations and can be absorbed through the respiratory tract, intestines, or skin.
Hydrogen sulfide is considered a poison that. affects several systems of the body, mostly the. nervous system. It is a colorless, flammable, and extremely hazardous gas with a rotten egg. smell. Hydrogen sulfide is similar to cyanide, and it. is five times more toxic than carbon monoxide. Natural hydrogen sulfide is found mostly in. swamps and sewers due to the breakdown of. organic matter and a lack of oxygen.