Sonet (1963) has mapped a plug about 2 km in diameter of a basic rock which is referred to as 'theralite'. However, from the brief description, the rock is not alkaline, although it may contain normative nepheline.
SONET, J. 1963. Notice explicative sur la Feuille Niéré. Carte Géologique de Reconnaissance à l'échelle du 1/500,000, République du Tchad.