Grit Table / naturals / British Slate
Product, no maker data
Natural stone
No particle size in microns is published for this line. The values are our estimates from secondary sources, so the marks are faded and the spread is unknown.
Each grade below shows its size in microns, its spread (the published distribution, where a maker or standard gives one; most makers publish none), and where that size lands on the reference scale, a shared yardstick for reading grit numbers across makers.
Range 1 to 4 µm. In production (Inigo Jones Slateworks).
Range 1 to 4 µm. Vintage / collector only: the Melynllyn ('Yellow Lake') hone quarry is marked disused on OS maps, no current production.
Range 1 to 5 µm. Historical / collector: no longer quarried, last (Whittle Hill) quarry closed in the early 1900s as imported Washita displaced it from ~1889; the source area is now a protected National Character Area.