A rich coverage of grey acicular köttigite-parasymplesite on/in a typical Ojuela Mine limonite matrix, in areas covered with a gypsum crust. Köttigite - Zn₃(AsO₄)2·8H₂O and its iron analog parasymplesite - Fe²⁺₃(AsO₄)₂·8H₂O and visually indistinguishable and probably form a Zn/Fe²⁺ solution series; either and/or both species may be present. Regardless, the association of these two species with gypsum is a Ojuela Mine classic.