gritstone

plural gritstones

1. countableuncountableA form of sedimentary rock, similar to sandstone but coarser.

   So Tom went to go down; and first he went down three hundred feet of steep heather, mixed up with loose brown grindstone, as rough as a file […]

   1863, Charles Kingsley, The Water Babies: A Fairy Tale for a Land Baby

   1 more example

   Adjacent to the roundhouse, but a little further north towards Curzon Street, are the surprising remains of the wagon turntables for the goods shed. Unusually, these are made out of solid gritstone so survive pretty much intact.

   2020 April 8, Paul Bigland, “Rail's future revealing railway's past”, in Rail, page 38