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| Gadolinite | |
|---|---|
 Gadolinite (black portion at top) | |
| General | |
| Category | Nesosilicate |
| Formula | (Ce,La,Nd,Y)2FeBe2Si2O10 |
| IMA symbol | Gad[1] |
| Strunz classification | 9.AJ.20 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) (sameH-M symbol) |
| Space group | P21/n |
Gadolinite, sometimes known asytterbite, is asilicate mineral consisting principally of the silicates ofcerium,lanthanum,neodymium,yttrium,beryllium, andiron with the formula(Ce,La,Nd,Y)2FeBe2Si2O10. It is called gadolinite-(Ce) or gadolinite-(Y), depending on the prominent composing element (Y if yttrium predominates, and Ce if cerium). It may contain 35.5% yttria sub-group rare earths, 2.2% ceria earths, as much as to 11.6% BeO, and traces ofthorium. It is found in Sweden, Norway, and the US (Texas and Colorado).
Gadolinite is fairly rare and typically occurs as well-formed crystals. It is nearly black in color and has a vitreousluster. Thehardness is between 6.5 and 7 on theMohs scale, and thespecific gravity is between 4.0 and 4.7. It fractures in aconchoidal pattern andstreaks grayish-green. It was also thought to exhibitpyrognomic properties, as it can emit visible light when heated to relatively lowtemperatures, but the scientific consensus is that this is the product ofthermoluminescence.[2][3]
Gadolinite was named in 1800 forJohan Gadolin, theFinnish mineralogist-chemist who first isolated an oxide of therare-earth element yttrium from the mineral in 1792. The rare earthgadolinium was also named after him. However, gadolinite does not contain more than trace amounts of gadolinium. When Gadolin analyzed this mineral, he missed an opportunity to discover a second element: the element he thought wasaluminium (alumina) was in factberyllium (beryllia), an element that was not officially identified until 1798.
Several elements were discovered as a consequence of lengthy analysis and decomposition of the ore gadolinite.[citation needed] As the ore was progressively analysed, the residue was first given the labelceria, thenlanthana, and subsequentlyyttria,erbia, andterbia. In order of date discovered, the list of elements includescerium,lanthanum,erbium,terbium,yttrium,ytterbium,holmium,thulium,scandium,praseodymium,neodymium anddysprosium. Several of these new elements were either discovered or isolated byCarl Gustaf Mosander in the 1830s and 1840s.
Gadolinite andeuxenite are quite abundant and are future sources of yttrium sub group rare earths. At present, these elements are recovered frommonazite concentrates (after recovery of ceria sub-group metals).