What usually happens to dollar-priced commodity prices when the US dollar strengthens?
A stronger dollar makes commodities dearer in other currencies, reducing demand and pressuring prices.
The concept: The US dollar and the dollar index
Cross-border commodity trade needs a common, convertible currency to avoid currency risk. Since the Second World War, the US dollar has been the main reserve and trading currency, followed by the euro. To capture currency moves simply, analysts use the dollar index: the dollar's strength against six currencies: euro, yen, pound sterling, Canadian dollar, Swedish krona and Swiss franc.