Stux, Rocky summit in Unkel, Germany.

Stux is a rocky hill above Unkel-Heister in the Rhein-Westerwald Nature Park, part of the right-bank Rhenish Massif. Its exposed sedimentary rock, about 325 million years old, consists of limestone slate in mostly horizontal but partly vertical bedding, visible where the layers break in the Unkel Fold. At its northern foot, the Stux waterfall drops beside the L252 in the Hähnerbach valley.

The Stux exposes a section of the Unkel fold, where layered sedimentary rock about 325 million years old breaks off visibly. These deposits of an ancient ocean, mainly horizontal but partly vertical, formed during the collision of Laurussia and Gondwana. Since 2005 the Rheinsteig long-distance trail has run directly over the hill.

The lower slopes feature vineyards that shape the local landscape and contribute to Middle Rhine wine production. Visitors can observe vineyard work throughout the seasons as they walk the surrounding paths.

The Rheinsteig long-distance hiking trail passes directly over the summit and connects to multiple paths within the Rhein-Westerwald Nature Park. The route offers good navigation markers and regular entry points from the valley below.

A radio transmission tower operated by Südwestrundfunk sits at the summit serving as a communications hub for regional mobile networks. The tower is clearly visible from the hiking trail and marks the peak's appearance.