A linear quarry, perhaps no more than a trial since there is no evidence that it led to an underground working, although the adjacent tip (520324) and the presence of a stone shelter (520325) suggest that it might have been a small mine. It is in the form of a linear cutting 18m E-W and up to 2m deep at the uphill end.
Part of the trials for slate quarries on Cae'r gors farm begun in 1870s (520443).
Recorded as part an Uplands Initiative field survey.
R Hayman, H&H, 27/8/2011.