I fresh water hunt in a natural lake that has a limestone bottom, i think thats what preserves them so well, i find wheats all the time that look like they just rolled out of the mint. : ) i do clean silver with a rock tumbler and boiling baking soda in aluminum foil, silver always comes out black, It is awesome to find V nickels that look the same as they did the day they where lost, i got a good spot, im very lucky