Since I started producing my own steel in a bloomery furnace, I spent some time checking 19th century/early 20th geological survey to find sutable ore deposits.
In my readings I discovered that there were a few quarries that produced grind stones and a couple where the quarried razor hones (I'm planning to check those during the summer).
I'm not sure what exactly those local stones are made of, still searching...
So i was wondering what was the composition of japanese water stones as to have something to compare those with. Is it the type of stone in itself or maybe "impurities" like the garnet in coticule stones?
Thank's for your help!