Which minerals are listed as indicators of rare earth element deposits?

• A. Quartz, Calcite, Feldspar, Gypsum
• B. Bastnaesite, Didymium, Loparite, Monazite
• C. Pyrite, Chalcopyrite, Galena, Sphalerite
• D. Olivine, Pyroxene, Amphibole, Biotite

Answer: (B)

Indicators of rare earth element deposits are minerals that host or concentrate REEs. Bastnaesite and monazite are classic REE-bearing minerals that commonly accompany REE mineralization. Loparite is an REE-rich oxide, and didymium (an historic REE-containing mineral) is associated with REE deposits. Their presence signals REE enrichment in the rocks. In contrast, the other mineral sets are common rock-forming or ore-related minerals that do not specifically point to REE mineralization: quartz, calcite, feldspar, and gypsum are widespread gangue minerals; pyrite, chalcopyrite, galena, and sphalerite indicate sulfide ore systems for base metals; olivine, pyroxene, amphibole, and biotite are typical silicates found in many igneous and metamorphic rocks and do not indicate REEs.