Muro's answer at Money SE discusses the attempt by brothers Nelson Bunker Hunt, William Herbert Hunt and Lamar Hunt to corner the silver mark. But Muro didn't explain the causation. I can't infer why this cornering caused gold prices to drop in 1981.
Since nobody is answering this, I will point out that the answer is half there.
- The cornering attempt directly affected the silver price, but gold went along for the ride. People treated gold/silver as an asset class - “precious metals” - and they traded them on a relative basis (the gold/silver ratio).
- The rules were changed, and the Hunts were forced to liquidate. This directly drove down silver futures.
- Gold went along for the ride. People who were long silver and gold got hit my margin calls, and they had to liquidate both. The gold/silver ratio would rise if gold did not move. Finally, people unaware of the details of the silver market would just view this as the end of the run for “precious metals.”
- Beyond that, it’s just opinions.