First finding of tiemannite, HgSe, in human bladder stones: An electron microprobe study

•Tiemannite, HgSe, was discovered, for the first time, in the human body.•Its crystallization is in equilibrium with the host bladder stone, mainly composed of struvite.•Tiemannite is classified as an endogenous biomineral, formed in the human body.•The precipitation of tiemannite in the human body can be considered a detoxification process.