Versionen im Vergleich

Schlüssel

  • Diese Zeile wurde hinzugefügt.
  • Diese Zeile wurde entfernt.
  • Formatierung wurde geändert.

...

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

...

Coarse-grained (cU, median ca. 1000µ); poorly sorted, angular.  angular