Rare earths and critical minerals

Perhaps the first question to ask about rare earth elements (REE) and critical minerals is what are they are and where they are? The US Geological Survey identifies around 50 “critical materials” judged to be essential for renewable energy projects, defence systems, and advanced manufacturing. REEs are a sub-set of this bigger group which are also used in applications such as mobile phones and wind turbines. Critical minerals also include lithium, copper, and nickel.