In The North Wales Quarrymen 1874-1922 by Merfyn Jones, mention is made on page 166 of "the old custom of the right to take home a round piece of slate". This is in relation to Llechwedd at around 1893 when C.W.Roberts was resident manager and having trouble getting the men to accept new rules. Ref. Y Genedl Gymreig. May,23. 1893.
Please, can anybody explain and expand on this custom?