Mundic—Iron pyrites.
Open Cut—A surface working.
Outcrop—That part of a vein showing on the surface.
Oxidation—A chemical union with oxygen.
Oxide—Combination of a metal with oxygen.
Panning—Washing gravel, or crushed rock, in a gold-miner's pan to detect gold, etc.
Peroxide—The oxide of any substance that is richest in oxygen.
Placer—A deposit of valuable metal in gravel.
Plat—A map from an original survey.
Plumbago—Graphite or black lead.