Abstract. The most common crystal forms of the diamonds from the alluvial deposits in the Western Region of the Central African Republic were examined by scanning electron microscope (SEM) in an attempt to determine their geological history. The marks observed are related to two distinct periods in the geological history of the diamonds: the magmatic episode and their hydraulic transport. The effects of significant magmatic corrosion undergone by the diamonds during their ascent from the upper mantle are shown by the predominance of rhombododecahedral forms over octahedral forms and the frequent occurrence on the crystal faces of pyramidal depressions with triangular (1 1 1) or square (1 0 0) bases, as well as of V-shaped figures (1 1 1) or stepped figures (on the faces around the ternary axes). Some impact marks probably occurred during the explosive episode of kimberlite extrusion. Other impact marks, the marks of general wear, and the high proportion of gemstone-quality diamonds indicate the lengthy transport. They thus also indicate that the diamonds have undergone a prolonged geological history after the erosion of the kimberlite. This
Le cortège des minéraux lourds recueillis sur la momie est composé principalement d'augite verte, suivie de hor-blende verte et de grenat. Le zircon et l'épidote sont peu abondants, la tourmaline et le rutile, rares. Ces résultats sont analogues à ceux de la Momie de Ramsès II, et surtout à ceux des sédiments de la vallée du Nil en Haute Egypte. Ils sont différents de ceux récoltés sur les momies et les sédiments de l'oasis de Douch ainsi que de ceux des sédiments de Basse Egypte. On peut donc émettre l'hypothèse d'une origine de la momie dans un site proche de la vallée du Nil en Haute-Egypte.
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