Gadolinite-(Y) Locality: Cuasso al Monte, Ceresio Valley, Varese Province, Lombardy, Italy Photo Copyright © Elmar Lackner

Chemical Formula: Y2Fe2+Be2Si2O10
Locality: Ytterby, Resarö, Sweden.
Name Origin: Named after the Finnish chemist, Johan Gadolin (1760-1852), who discovered yttrium. The element gadolinium was also named after Johan Gadolin in 1880.

Gadolinite, sometimes also known as Ytterbite, is a silicate mineral that consists 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 prominence of the variable element composition (namely, Y if it has more yttrium, and Ce if it has more cerium). It may contain 35.48% yttria sub-group rare earths, 2.17% ceria earths, up to 11.6% BeO and traces of thorium. It is found in Sweden, Norway, and the USA (Texas and Colorado).

Physical Properties

Cleavage: None
Color: Brown, Green, Green black, Light green, Black.
Density: 4 – 4.5, Average = 4.25
Diaphaneity: Subtransparent to opaque
Fracture: Splintery – Thin, elongated fractures produced by intersecting good cleavages or partings (e.g. hornblende).
Hardness: 6.5-7 – Pyrite-Quartz
Luminescence: Non-fluorescent.
Luster: Vitreous – Greasy
Streak: greenish gray


Gadolinite-(Y) Locality: Ytterby, Resarö, Vaxholm, Uppland, Sweden Dimensions: 2.3 cm x 2.2 cm x 2 cm “Courtesy of Rob Lavinsky, The Arkenstone,”
Gadolinite-(Y)-Gadolinite-(Ce) Locality:North Sugarloaf Mountain, Bethlehem, Grafton County, New Hampshire Overall Size:    13x11x8 mm Crystals:5-6 mm Photo Copyright © JohnBetts-FineMinerals
This sample of gadolinite is displayed in the Smithsonian Museum of Natural History. This gadolinite specimen is about 15 cm across and is from Iveland, Norway.
This sample of gadolinite is displayed in the Smithsonian Museum of Natural History. The sample is about 15 cm across and is from Saetersdalen, Norway.
Norway © 2001 John H. Betts