The Loraboue prospect is located in the northern part of the Poura district, in the Boromo greenstone belt (Burkina Faso). Gold mineralization occurs in albitized rock (albitite) and carbonatized ultrabasic rock (listvenite), which represents a new type of ore deposit in Burkina Faso. The precipitation of gold can be achieved during the late stage of alteration inducing the crystallization of ankerite, quartz and muscovite in albitite, and ferroan-magnesite, fuchsite and quartz in serpentinized ultramafic rocks. Gold deposition is linked to the formation of sulfides (mainly pyrite associated with quartz), itself controlled by the Fe/(Fe+Mg) ratio of the initial host-rock. This could explain the higher Au contents of albitite (0.5<Fe/(Fe+Mg) <0.9; 5 to 1250 ppb Au) than hydrothermalized ultrabasic rock (0.1<Fe/(Fe+Mg)<0.2; 10 to 200 ppb Au). These unusual rocks could represent an attractive target for Au prospecting in the Burkina Faso.

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