L327 Sandstone, ferruginous

Mainly medium sand (to coarse sand in the case of L327a). 
Yellow-brown iron stained quartz, cemented by the same yellow brown oxide. A few larger quartz grains up to 5 mm long. Grains are angular to sub-rounded, and poorly sorted. 
Fizzing with acid, indicating that there is a carbonate cement.

Angular to sub-angular grains of quartz, displaying undulose extinction. 
Most have thin brown rims of iron oxide. 
A few grains of feldspar. 
Minor carbonate cement (sparite).

Deposited in an aqueous environment, since it is not clean enough to be aeolian.

Iron staining 
Hematite (Fe₂O₃) → red (blood-red, cherry-red, brown-red) iron-staining 
Limonite (FeO(OH)•nH₂O) → yellow or brown iron-staining

The yellow colour of this rock is probably produced by limonite.