The mountain is made up of grey limestone with a cap of sandstone and shales and is extensively quarried by local companies. The surface is mostly covered with peat, conifer forests and grazing fields. The mountain contains several caves and swallow-holes including Pollnagollum (Slieve Rushen) and Tory Hole which are a popular destination for potholers, both situate in Legavreagra townland. It forms part of the Slieve Rushen Bog Natural Heritage Area . A recent addition to the mountain is the Slieve Rushen Wind Farm for generating electricity.