Depends on how far away you are from retirement.
If you aren’t retiring within the next 15-20 years, I’d put most of your $ in mutual funds/ETFs/stocks.
You would expect gold and silver to do the opposite of the stock market, but they are not. Gold today is worth less than it was in 2012, and has been up and down since then.
If you are close to retirement & want to “preserve your assets”, buy bonds or get a money market account. But you really aren’t preserving them, as these type of investments aren’t going to keep up with inflation.
PMs can be just as volatile as stocks and there is no way to predict what will happen with them. At least the stock market, (long term) seems to give you more predictable results.