I know Croesor well although not the slate mine to well
I often visited a farm at Croesor with my sister who was a friend of the owner who specialised in making walking sticks
I purchased one and i still have it today some 20 odd years after i Purchased it

My sister is Vice President of The Brythoniaid Male Voice Choir at Blaenua Ffestiniog her son was one time a resident at Blaenau a Manager / Lecturer at Bangor University he now a Lecturer at Leeds university and also one time an adviser to The Welsh Assembly

He lived at the foot of The Crimean Pass near the Slate Quarry living near a member of my family whose kin were Slate Quarrymen at Blaenau

I was one time an Hon Member of The Moelwyn Male Voice Choir

Other members of my distant family lived at Porthmadog
whilst my Uncle Rev Sidney Austin Price was Methodist Minister at Ruabon in the Llangollen Circuit in the 1950s I often staying with the family there.. At one time in my late teens I was going to work for the Forestry Commission who had a site near Llangollen but it all fell through when i failed the medical