L326 - Sandstone, ferruginous arenite

Specimen Age

Permian

Location

Penrith Sandstone
Appleby, Westmorland

Hand Specimen

Reddish brown rock. Medium sand grade.
Round to sub-round grains of quartz, often with a thin rim of red hematite. Mainly reddish and pink-brown grains, fewer white grains and very few black grains. Well sorted and well cemented.
No fizzing with acid, so does not contain significant carbonate. 

Laminations can be observed in sample L326b. There is an inter-layering of coarser and finer laminae.

Thin-section

Fine laminations can be seen when the thin-section is held up to the light. 
Moderately well rounded quartz grains with thin rims of hematite, and overgrowths of quartz in optical continuity with the original grain. 
Occasional grains of very fine quartzite, microcline, plagioclase, mica and decomposed fine-grained igneous rocks. 
Siliceous cement and the secondary quartz overgrowths hold this rock together.

The grains are finer as a whole in L326b, and less well rounded.

Rock History

Probably deposited in an aeolian environment, since it almost entirely comprises well sorted and well rounded quartz grains.

Rock Name

ferruginous sandstone
ferruginous arenite
L326 - Sandstone, ferruginous arenite