Penrhyn and Dinorwig became the two largest slate quarries in the world. The Oakeley mine at Blaenau Ffestiniog was the largest slate mine in the world. In 1898, a work force of 17,000 men produced half a million tons of slate.
N ewmont Slate Company produces the most and finest Vermont Black Slate in the United States. Newmont President and CEO, John (Jack) Williams has been in the slate quarry business for more than 50 years. With one of the largest and most modern facilities in the slate industry, Newmont Slate Company and it's numerous quarries in Vermont produce an exceptionally highquality stone for .