The Municipality of Hrastnik (Slovene: Občina Hrastnik) is a municipality in central Slovenia. The seat of the municipality is the town of Hrastnik. Traditionally the area was part of the Styria region. The entire municipality is now included in the Central Sava statistical region. Located in the valley of a minor left bank tributary of the Sava River, the area is known for its rich deposits of coal. Coal mining began in the area in 1804. Surrounding peaks include Mount Kum (1220 m), Mount Mrzlica (1122 m), and Kopitnik Hill (910 m). The area around Kopitnik is protected as a nature reserve. Species such as the capercaillie and chamois run wild in the surrounding forests.