According to an article in this week's Economist magazine (Feb 23-Mar 1, 2019) scientists have discovered a treasure trove created by a kilonova, which occurs when two neutron stars collide. ("The ultimate nuclear reactor", page 77-78) Apparently they reckon some 10 x the mass of Earth in gold was created along with 50 x the mass in platinum. That's a tidy sum!
Unfortunately, it is located in a distant galaxy in the Hydra Constellation. And the event occurred a long time ago. But, otherwise, the next Gold Rush could be just around the corner!
Of course, flooding the market with that much gold and platinum would drive the prices down, however, spread across the many worlds of an Interstellar Empire some Mega-corp could stand to clean up a tidy fortune, or fortunes.
There's scope in there for some retro-sci/fi or pulp scenarios, methinks...
