Dally Slate Quarry


Slate has been mined in the town of Pen Argyl since the 1850’s, but today, the Dally Quarry is the only remaining active quarry in the area.  The Dally family purchased the quarry, formerly known as the Diamond Quarry, in 1996.  Geologically, slate develops in paths called veins that can run hundreds of feet deep.  Each path is named and followed by miners.  The hole at Dally Quarry is currently approximately 350 feet deep. To extract the slate, three or four miners go to the bottom of the hole and cut and loosen the slate.  One man, the engineer, is positioned at the top of the hole (Ray, pictured in a photo), and operates the hoist that lifts the slate to ground level.  The slate is then transported to the mill (usually on-site) where approximately ten men work on splitting and processing the slab.  In the 1950’s, the mines employed more than 100 workers, at a time when there was greater demand for slate.  Today, the Dally Quarry only employs about fifteen people at any given time.  Even on this diminished scale, pride in the history of the industry and the work of slate mining is present among these workers.