Oh, the mining company management will know what the spot price in dollars is and if the spot price offered in cedis doesn't seem fair. But "we've found a cunning new way to exploit our gold reserves" is a better PR line to the general public than "we're fudging the figures a bit in our favoir*

Look at HN's somewhat sophisticated audience heralding it as a power move against the dollar rather than a country scrabbling around for ways to dig itself out of a financial hole caused in part because the dollar holds value much better than their own currency.

It strikes me as a tax on gold mining. I can't think of any principled reason why they shouldn't do that, to raise money for their government.

Indeed, having a better engineered money system is one of the things that make rich countries richer.