. If they’re not rare, are they very expensive?
Yes, quite. In 2018, the cost for an oxide of neodymium, atomic number 60, is US$107,000 per metric ton. The price is expected to climb to $150,000 by 2025.
The numbers are different in this article.
What are rare earths, crucial elements in modern technology? 4 questions answered
https://theconversation.com/what-ar...modern-technology-4-questions-answered-101364