Levels at NY810606 and NY814606
Marked on first series 6 inch OS as coal levels. There are also, apparently later, shaft workings in the field to the north, above the cleugh.
An article by Dennis Telford in the Haydon News has this to say about Harsondale.
Three unnamed fatalities are recorded at Harsondale Colliery, on 5th June 1851 (falls of stones and coal), 29th July 1851 (choke damp) and 31st July 1852 (crushing).
In the 1900s Harsondale Colliery was owned by the Langley Barony Coal and Fireclay Co. Ltd., and from 1914 until 1925 it was managed by John William Stobart.
Harsondale was mainly a fireclay mine from 1948 and it closed in 1952.