The Deposit

The exploited area has the shape of a straight band, which stretches from AVTA in the Southwest 10 km from the coast, to beyond DAGBATI in the Southeast.

  • Longth: 35 kilometers;
  • Maximum width: 2.5 kilometers;
  • Thickness (or power): 4 to 6 meters

The layer whose roof (the upper layer) is roughly horizontal has s discontinuity in its length due to erosion. The most important of these cuts extends from KPOGAME to HAHOTOE over 6 kilometers and corresponds to the valley of HAHO and its tributaries, a second cut is located at DAGBATI, thus delimiting the deposit in three tasks.

  • In the South: the AVETA-KPOGAME task;
  • In the center: the HAHOTOE-AKOUMAPE task;
  • In the North: the DAGBATI task.

The thickness of the covering varies from 7 to 40 meters.

A structural section perpendicular to the axis of the deposit, in AKOUMAPE region, represents the known part of phosphate formations. It stretches for 6 km without losing sight of the phosphate which, however, becomes scarce gradually giving way to the original matrix, light, gray rock, and rich in organic material. On the left in the North, we can see the LAMA depression. In the Southwest, the natural land follows a slope where it is the VOGAN-ATTITOGON plateau. The phosphate formation slopes about 1% to the Southeast.

The mining of the deposit

The mining area indicates the width of the high-grad deposit, non-calcified part of the layer. On the section on the ground appear from bottom to top:

  • Attapulgite clays, Paleocene in formation and of geographical uniformity.

  • The layer (3), consisting of a gravelly ore with rosin kidneys, coprolites and bone debris. It is very heterogeneous, often washed      out by underground currents, spreads, of low power and is located under a significant covering.

  • The layer (2), regular of about ten meters of power, very poor in phosphoric anhydride and basically made up of a finely powdered      marl.

  • A compact clay bed, remarkably continuous and of modest thickness (2.5 meters at most). It’s a marly background.

  • The layer (1), made up of a calcareous formation, occupying three-quarters of the crossing and a phosphate deposit     (phospharenite with clay matrix) practically devoid of calcium carbonate, very rich in phosphatic anhydride and part of which is      object of exploitation. The calcareous deposit (phospharenite with carbonate gangue) constitutes a very important reserve of an      ore less rich in phosphatic anhydride than the previous one.

  • The layer (0), stacking of phosphate, coprolithic and clay layers, depleting upwards. The ore is very fine and very colored by iron      oxide.