Rottenstone

Rottenstone (sometimes spelled as two words and also known as "tripoli") is weathered limestone that is mixed with diatomaceous, amorphous or crystalline silica. It is often used for polishing metals and distressing water gilded surfaces to reveal bole and lay-lines. The grey color makes it a desirable antiquing dust. It has similar applications to pumice, but it is a finer powder and used for a more glossy polish after an initial treatment with (fine granularity) pumice powder. It is usually mixed with oil, sometimes water, and rubbed on the surface of varnished or lacquered wood with a felt pad or cloth. Rotten stone is sometimes used to buff stains out of wood. Some polishing waxes contain powdered rotten stone in a paste substrate. For larger polishing jobs, rotten stone mixed with a binder is applied to polishing wheels.