emery

smirgeli puhekieltä An impure type of corundum, often used for sanding or polishing.
1884, Samuel Smiles, Men of Invention and Industry

It took me from nine to ten days to grind and polish it ready for parabolising and silvering. I did this by hand labour with the aid of emery, but without a lathe. I finally used rouge instead of emery in grinding down the glass, until I could see my face in the mirror quite plain.