We live across from a limestone pit...I've found a used dryer sheet moistened with water is mildly abrasive,but whatever is in the dryer sheet cuts all the crud at the base of the sink fixtures.
We also use it for pots with burned on foods. Just put the dryer sheet in the pan (after it has cooled, of course), add water, let sit overnight...use the dryer sheet the next day as a scrubby, and viola'! Burn junk is gone! Dryer sheets do a lot of things...we store the used ones in an empty tissue box.