Gaisberg, Mountain summit in Molln, Upper Austria, Austria

Gaisberg is a 1267 m high, largely forested mountain in the Upper Austrian Prealps within the municipality of Molln. A marked hiking trail leads over the summit; to the west lies the Dürre Eck at 1222 m, and to the south the Mollner Hütte at 1005 m. Limestone is quarried on the mountain by the Bernegger company.

Iron mining on the Gaisberg is documented from around 1570, when the former Steyr mayor Sebastian Pürschinger and the blade-maker Christoph Aichperger obtained imperial permission and opened three pits on the mountain. Emperor Rudolf II granted the same rights to the Innerberg hammer masters Murschhofer and Forster in 1604. After the ore was exhausted around the end of the 18th century, the last mining lease followed in 1787, and the iron-mining rights lapsed in 1882.

The name Gaisberg refers to the mountain's historical iron ore mining, documented from around 1570 when Sebastian Pürschinger and Christoph Aichperger opened three pits here. Remains of the Molln mining huts lie near Gstadt. Today the Bernegger company quarries limestone on the mountain, and the Pfaffenboden pit is linked to the valley by a 3.5 km tunnel.

Multiple marked routes start from Molln and reach the summit with varying difficulty and duration to complete. During winter months, sturdy footwear and equipment like trekking poles are needed since snow and ice alter trail conditions.

The old quarry at Dürres Eck was renaturalised after a 2000 decision; mining moved to Pfaffenboden, where crushed limestone runs down a 3.5 km tunnel at 15% gradient and the braking energy generates up to 495 kWh fed into the company grid.