Crocoite is a mineral, lead chromate, PbCrO4, that crystallizes in the monoclinic system. It was discovered in the Berezovsk deposit, near Yekaterinburg, in the Ural Mountains. It was described by Mikhail Lomonosov as red lead ore, although the description was necessarily incomplete, since one of the constituent elements, chromium, was not yet known. When Vauquelin discovered chromium in this mineral, he used the name Siberian red lead for the mineral itself.