Definitions:

1. A dark green to black, hard radioactive mineral, that is an ore of various rare-earth elements. NOUN
   • Gadolinite is an important mineral for collectors of rare elements and minerals.
2. A mineral of a nearly black color and vitreous luster. NOUN
   • Gadolinite is used as gemstone in jewelry and other decorative objects.
3. A mineral that typically occurs as a rare earth metal yttrium-beryllium-iron-aluminum silicate. NOUN
   • Gadolinite is found in many parts of the world including Scandinavia, Russia, and the United States.

Synonyms:

• eucryptite
• graftonite
• mineral
• ytterbite