The pit called Barbara is by all means the department's most attractive part. It was named after St. Barbara, protectress of the miners. Built in 1963, it presents subsurface exploitation of mineral ores.

The part of the mine suggesting conditions proper to subsurface coal exploitation includes the mine's main rooms and their respective purposes. The ingenuity accompanying the calling is illustrated through over a hundred supporting details. They include different kinds of wooden supports (used in coalmine hallways), permanent mine rooms (built in brick, stone blocks, concrete, and the like); supports used on collection and exploitation sites, as well as ventilation devices. Of particular interest is the fact that the model includes some exact replicas of the former Zagorje region coalmines in their actual size, as well as those of the Rasa pit coalmine: Hallways serving different purposes (transportation, ventilation), active and old (abandoned and caved in) sites, as well as other mining-related objects (fire-protection walls, ventilation openings, and the like).

Apart from coal exploitation presentation, visitors may also see the ways of exploiting other mineral ores, such as bauxite, lead/zinc/silver ore, and iron.