rottenstone
/ˈrɑtənˌstoʊn/
noun
- A soft, fine-grained stone (often decomposed limestone or siliceous rock) used as a powder for polishing metals, marble, and other surfaces.
- He used rottenstone and oil to polish the brass candlesticks to a high shine.
- For a smooth finish on the marble countertop, the craftsman mixed rottenstone with water.
- The jeweler applied rottenstone with a soft cloth to buff the silver ring.