Rare Metals are found only in underground deposit sites and need Rare Metals Extractors to mine them. They are mostly used for manufacturing electronics and for exporting back to Earth.
The Mohole Mine will extract both Metal and Rare Metal. No buildings require rare metals to either be built or for maintenance.
Background[]
After millennia of acting as a status symbol, in modern times rare metals are widely used in electronics and for medical procedures. Still, although one of the vital elements of the Information and Space Ages, precious metals still retain their monetary role.