Lone Mountain is an 11,167-foot summit in Montana’s Madison Range, with its peak in the Lee Metcalf Wilderness where Gallatin and Beaverhead-Deerlodge National Forests meet. Although made of igneous rock, it is not a true volcano because its magma never reached the surface; instead, it is a laccolith formed when intrusive rock pushed upward beneath older layers. The mountain is both a protected natural feature and a major recreation landmark. Big Sky Resort occupies its east, north, and southern slopes, tying Lone Mountain closely to one of Montana’s best-known ski areas while leaving the summit within designated wilderness.