Guettardite is a rare arsenic-antimony lead sulfosalt mineral with the chemical formula Pb(Sb,As)2S4.
It forms gray black metallic prismatic to acicular crystals with monoclinic symmetry.
It was first described in 1967 for an occurrence in the Taylor Pit, Madoc, Hastings County, Ontario, Canada.
It occurs associated with pyrite, sphalerite, wurtzite, galena, stibnite, orpiment, realgar, enargite, tetrahedrite, zinkenite, jordanite, bournonite, sterryite, boulangerite, jamesonite and sartorite at Madoc.
[3] In addition to the type locality, it has been reported from the Brobdingnag mine, near Silverton, Colorado; the Jas Roux deposit in Hautes-Alpes, France; from various marble quarries near Seravezza, Tuscany, Italy; a marble quarry in Valais, Switzerland and from Khaydarkan, Fergana Valley, Alai Mountains, Kyrgyzstan.