Fluvial sand, Wouri River, Cameroon
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Glass bead is 200µ in diameter |
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Location:
Shore of the Wouri river (25 km from the Atlantic ocean), City of Douala (long. 9 42'; Lat. 4 3'), Cameroon
Provenance:
Mix of (1) ?volcanic source rich in quartz with (2) ?basaltic gas-rich lava; also, (3) some arid-climate components
Composition:
Dominant typically blocky, highly angular transparent and clear, occasionally slightly yellowish quartz (volcanic or high-grade metamorphic provenance ?). Significant (~5%) component of fresh black glassy bubbly lava (resembling pumice), few wind-abraded grains with desert varnish; very few grains of chlorite/epidote minerals. Interesting incongruent composition. Traces of well rounded quartz grains and recent plant seeds
Texture:
Coarse-grained (cU, median ca. 1000µ); poorly sorted, angular