NEHL - An old shaft is labelled here on the Ordnance Survey maps from the 1890s, and was certainly out of use by this date.

It's very likely this was Greenside Colliery's A Pit, with the B Pit located north east on the other side of the village. This isn't to be confused with the 20th century Greenside Pit which was sunk directly south and probably utilised some of the same workings.

This colliery was much more modest, probably sunk after the 1850s and was closed only a few decades later. The complex was small, only taking up a few dozen or so square metres with one single building on the surface, which leads to speculation this was never the main pit but secondary and perhaps ventilation.

Unfortunately the only view we have is from the 1890s, when the shaft was no longer worked. It was reopened when the Greenside Pit opened in the mid 1900s by the Stella Coal Co, featured here: https://www.northeastheritagelibrary.co.uk/coalsarchive/6992a/greenside-pit

It no longer exists, and a fairly modern housing development now takes its place.