Gadolinite-(Ce) Locality: Tuftane (Tuftan; Tuptane), Frikstad (Frigstad), Iveland , Aust-Agder , Norway ( Locality at mindat.org ) Size: small cabinet, 8.2 x 7.1 x 5.2 cm Gadolinite-(CE) A huge gadolinite crystal from one of the old classic locales for this species, and from the John Sinkankas collection. It masses 583 grams which is VERY hefty when held, and is a giant crystal - the big ones seldom maintain such sharp form. Sinkankas, a renowned author and collector, noted its value as $125 in 1968 (he purchased for a bargain price of $20 in 1965 - but that was a lot of money then, too, for an ugly rock!), and wrote that it is "Very large, sharp, and exceptional" on his original label, an index card in his hand which accompanies the piece. I purchased this directly from John at his home in San Diego in about 1998, and sold it to collector Bob Nowakowski , who had a large suite of exceptional crystals of the Rare Earth Elements species. He held it until recently. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Gadolinite-(Ce)
Gadolinite, sometimes known as ytterbite, is a silicate mineral consisting principally of the silicates of cerium, lanthanum, neodymium, yttrium, beryllium, and iron 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 of thorium. It is found in Sweden, Norway, and the US (Texas and Colorado).
Intro adapted from Wikipedia (CC BY-SA).
Gadolinite-(Ce) is an IMA-recognized mineral species in the silicate class, with the chemical formula Ce₂Fe²⁺Be₂O₂(SiO₄)₂.
It crystallizes in the monoclinic crystal system. It is a member of the Gadolinite structural group.
Key properties: Mohs hardness 6.5–7; specific gravity 4.2; Vitreous luster.
IMA symbol Gad-Ce, IMA status: approved, named in 1978.
Found in syenite pegmatite veins along a contact between basalt and monzonite.
It is found associated with Aegirine, pyrochlore, zircon, apatite, titanite, pyrophanite, magnetite, loparite, chevkinite, biotite, microcline, helvite, molybdenite, albite, apophyllite.
The name refers to its cerium content and relation to gadolinite-(Y).