One could also imagine an event where a small cluster of meteorites moving through the solar system did not get pulled into the asteroid belt, but instead showe

One could also imagine an event where a small cluster of meteorites moving through the solar system did not get pulled into the asteroid belt, but instead showered the Earth for a few decades, or even a century, with a few impressive streaks in the sky every year. Even if only one landing site in ten was identified, you may have dozens of sources of pure ore.