there are many different types of polishing compounds in various forms (powder, suspension, solids, etc) that consist of an abrasive of some sort, and some type of vehicle to allow it to be applied to whatever will be doing the polishing (a cloth, buffing mop, cast iron hone, etc). some ingredients are listed below.

abrasive comments
chromium(III) oxide green powder, mohs hardness of 8-8.5
aluminum(III) oxide white powder, mohs hardness of 9 (corundum)
synthetic diamond clear to opaque, mohs hardness of 10
vehicle comments
stearic acid fatty acid found in plants and animals, waxy at room temperature and fairly safe. used to impregnate mops, strops, and tin laps
kerosene petroleum distillate used to create a slurry when working with cast iron or other metal hones/laps
naptha same as above