L324 Sandstone, feldspathic arenite

L324_HS.jpg
L324_TS_ppl.jpg
L324_TS_xpl.jpg

Title

L324

Sandstone, feldspathic arenite

Subject

Age

Precambrian

Location

Torridonian Group, North West Scotland

Description

Hand Specimen

Reddish brown rock made up of pinkish feldspar, colourless quartz, and some dark grey grains. Medium to coarse sand. Moderately rounded. Fairly well sorted. 
Contains <15 vol% clay, so this is an arenite. 
No fizzing with acid, so does not contain significant carbonate.

Thin-section

Quartz (~65%) 
- Includes fresh quartz grains with undulose extinction, quartzite grains with internal sutures, and quartz vein material. Some quartz grains have opaque rims.

Feldspar (~35%) 
- Mainly microcline, some plagioclase. Some microperthite texture and decomposition to clays.

All grains are moderately rounded and fairly well sorted. The rock is well compacted. A thin film of cement mainly hematite and clay coats the grains.

Rock History

This rock contains too much feldspar, and the grains are not sufficiently well rounded nor well sorted to have been deposited in an aeolian environment. The sediments were deposited in an aqueous environment.


Rock Name

sandstone
feldspathic arenite

Citation

“L324
Sandstone, feldspathic arenite,” 1A Collections, accessed April 9, 2024, https://wserv3.esc.cam.ac.uk/p1acollections/items/show/23.