On an industrial park about an hour¡¯s drive toward the South China Sea coast from Ho Chi Minh City sit giant mounds of raw metal shrouded in black tarpaulin. Stretching a kilometer in length, the much-coveted hoard could be worth about $5 billion at current prices.

In the esoteric world of aluminum, those in the know say the stockpile in Vietnam is the biggest they have ever seen ¡ª and that¡¯s in an industry that spends a lot of time building stockpiles while analysts spend a lot of time trying to locate them. But as far as the increasingly under-supplied market is concerned, it¡¯s one that may never be seen again.

Why it¡¯s unlikely to move anytime soon involves Vietnam¡¯s customs authorities. How its existence has become so significant, meanwhile, opens a window on a ubiquitous, yet erratic commodity at a time when makers of everything from car parts to beer cans are competing for more of it as they emerge from the COVID-19 pandemic and China throttles supply.