Definition of gadolinite in US English:



  • A rare dark brown or black mineral, consisting of a silicate of iron, beryllium, and rare earths.

    • ‘The most common ores of holmium are monazite and gadolinite.’
    • ‘It is found with other rare earth elements in minerals such as monazite, cerite, gadolinite, xenotime, and euxenite.’
    • ‘With sulphuric acid it forms a salt that is as stable on heating as the sulphates from gadolinite or cerite and, like these, can be completely decomposed by heating with ammonium carbonate.’
    • ‘Like other rare earth metals, it is found in minerals such as cerite, gadolinite, and samarskite.’
    • ‘Polycrase, or an allied species, was seen implanted upon the gadolinite, this is also new to the region.’


Early 19th century: named after Johan Gadolin (1760–1852), the Finnish mineralogist who first identified it.