To start with, if the primary metal is smelted and cast in North America, either in Canada, the United States or Mexico, it is easy to know where it comes from and where it is processed, using the standards of the Aluminum Stewardship Initiative, the ASI, of which Rio Tinto is a part. That ensures the quality of the aluminum all along the production chain, from bauxite to alumina, right to the customers.
On February 25th, 2020. See this statement in context.