Jebel Arkenu is a smaller copy of Jebel Uweinat, lying about 25 kilometres to the north-west. It is a similar smaller granite ring complex, with a broken interior drained by one main wadi system. To the north east there is the much eroded remnant of a sandstone massif adjacent to the granite dome.
A large akacia or "arkenu" tree stands at the mouth of the main wadi, that gave the mountain it's name. Further in, the wreck of a french built armored car guards the track leading in, probably a relic of the war in Chad.
Far upstream there is a spring in the wadi bed that goes dry after prolonged aridity. As the mountain is much lower than Uweinat, it can capture much less rainfall, and this shows in the very dry and sparse vegetation. Due to it's smaller size and few rock art sites it remained little explored untill the Sandhurst Academy expedition made a detailed survey in 1962. Yet much of the north-eastern part of the mountain remains unsurveyed.
To the north of Arkenu there are two more eroded granite massifs straddling the Libya - Egypt border, Jebels Bahari and Babein.