Peter/peter out

Peter, meaning to stop or leave off, is cited by the OED as slang or colloquial dating from 1812. It then goes on to give ‘peter out’, meaning to diminish or run out, as in a vein of ore, as a US mining colloquialism dating from 1865. The origin is unknown. Attempts to link it with St Peter and saltpetre (US spelling saltpeter), which was used in mining operations, have proved fruitless.