L325 - Sandstone, calcareous cement

Hand Specimen

Pale grey rock, mainly medium to coarse grained quartz sand. Poorly sorted. 
Small amounts of lithic fragments up to 10 mm across, and shell fragments. 
Contains <15 vol% clay, making it an arenite.
Pale grey cement fizzes with acid, indicating that it is carbonate.

Quartz grains, sub-angular to sub-rounded, occasionally rounded, displaying undulose extinction. 
Lithic fragments including flint and quartzite. 
Some grains of feldspar. 
Rare small green clasts. 
Grain supported. 
Cemented by a sparry calcite cement. The cement crystals are large, each enclosing a number of sedimentary grains.

Deposited in an aqueous environment; grains are not rounded enough to have been deposited in an aeolian environment.

The rare green clasts are made up of a cryptocrystalline material, which may be a type of amphibole called glauconite, and some rather decomposed rhyolite or andesite.

calcareous sandstone
calcareous arenite