The Mandara Mountains are of volcanic origin. The Range extends 200 kilometres along the Cameroon-Nigeria borderline. Its highest point is the Mount Oupay at 1'494 metres.
Cameroon 1947/1961, Piton d’Humsiki.
Cameroon 1962, Piton d’Humsiki.
Cameroon 1980, Piton d’Humsiki.
Liberia 2001, Wildlife in Africa.
It seems, the illustration depicts the Piton d’Humsiki.
Republic of Guinea 2008, "La Chine en Afrique".
Part of the illustration is showing the Piton d'Humsiki.
The stamp is showing the Victoria Falls (Eastern Cataract) in the background.
Lansana Conté (1934-2008), President of Guinea from 1984-2008.