Pitted, Pitting. Multiple indentations on the surface of a numismatic item caused by rusting, corrosion, fire damage or mishandling. On a struck piece pitting usually indicates corrosion or mishandling and the piece is severely downgraded in condition. Pitting in a die usually is caused by rusting which results in raised lumps on any piece struck from such an impaired die; each lump is called a boss. Rust pits in the die are usually located in the highest part of the die near relief, this is the lowest part of the struck piece, usually

in the field. Some rust bosses may be removed by chasing if a fresh piece needs to be struck from an old die (as for an award medal). See rusted dies, rust pits.

Reference:

NE42 {1882} Doty, p 259-260.