Slate (writing) expensive. Slate (writing) A slate is a thin piece of hard flat material, such as the rock also called slate, that is used as a medium for writing. The rock is “a metamorphic rock created by the recrystallization of the minerals in shale from clay to parallel-aligned, flat, flake-like minerals such as mica”. The writing slate consisted of a piece of slate, typically either 4x6 inches or 7x10 inches, encased in a wooden frame. A precise date range for writing slates of this type has not been established. Usually, a piece of cloth or slate sponge was used to clean
Aberllefenni Slate Quarry Aberllefenni Slate Quarry Aberllefenni Slate Quarry is the collective name of three slate quarries, Foel Grochan (sometimes misspelt as Foel Crochan), Hen Chwarel and Ceunant Ddu, located in Aberllefenni, Gwynedd, North Wales. It was the longest continually operated slate mine in the world until its closure in 2003. Foel Grochan is the quarry on the eastern side of the valley, facing Ceunant Ddu and Hen Gloddfa on the west; all three were worked as a single concern throughout their history. Technically all three of these are mines, not quarries, since all rock extraction takes place underground, though they are often