The bullion was discovered in the carriage of a Swiss Federal Railways train travelling from St Gallen to Lucerne in October last year.
Officials said the owner of the 3kg haul of gold could not be tracked down despite "extensive investigations".
In a statement, published in the local Government Lucerne Canton Gazette, authorities said the parcel has been confiscated by the public prosecutor's office.
The discovery has now been made public in the hope the owner will come forward.
Officials said the owner has five years to make a claim.
Simon Kopp, the information officer for the public prosecutor’s office of Lucerne, told CTVNews that the gold was discovered in a parcel by a train worker, and that they do not suspect it is connected to any crime.
According to Swiss Info, the Swiss Federal Railways’ centralised lost and found service receives around 300 objects a day that have been left behind on trains.
The most valuable misplaced object remains a 1727 Stradivarius violin left behind in 2012.
The violin was believed to be worth around €2.4 million (£2.1 million).
