"New York Mining Disaster 1941" by The Bee Gees.
OK, boys and girls, more 60s: This Beatles-inspired 1967 Bee Gees tune was their first U.S. release and their first chart single in the U.S. (#14) and the UK (#12). A trapped man yearns for his wife as his life fades away. The "mystery" opening chord is played by Barry using an open D tuning but playing a conventional A-minor chord shape (!). Song? Answer: "New York Mining Disaster 1941" by the Bee Gees. As opposed to Pete Seeger's and The Byrds' "The Bells Of Rhymney", this disaster never happened. I remember listening to this song for the first time with my dear friend Ralph Yunque and wondering where in the world that vocal vibrato came from. The opening chord sounded somewhat like an A-minor but not quite - aha, now we know the mystery! There were rumors early on that The Bee Gees were The Beatles recording under a coded pseudonym for "Beatles Group"! https://www.youtube.com/watch?v=S43YhQ_eGTw