Gadolinite

Formula: (Ce,La,Nd,Y)₂Fe²⁺Be₂Si₂O₁₀
Two different gadolinites do exist: Gadolinite-(Ce) with more Cerium, Gadolinite-(Y) with more Yttrium.
Mineral class: silicates
Crystal system: monoclinic
Mohs scale: 6.5 - 7
Density (g/cm³): 4.36 - 4.77
Refractive index: 1.78
Cleavage: -
Colors: colorless, tan, brown, green, black
Transparency: translucent
Luster: vitreous
Fluorescence: -
Pleochroism: -
Largest crystal: 2 cm?
Deposits: Austria, Germany, Italy, Japan, Norway, Russia, Sweden, USA
Discovery: 1788
1st Description: 1794 (Gadolin)
Name: in honor of the Finnish mineralogist Johan Gadolin (1760 - 1852)
If the mineral contains Thorium, it is radioactive

Gadolinite-(Y) Mineral

Image width: 0.3 cm

Origin: Furka basis tunnel / Oberwald / Goms / Wallis / Switzerland

Photo by kind permission of © Stephan Wolfsried

Gadolinite-(Y) Mineral

Size of the crystal: 0.07 cm

Origin: Hopffeldboden / Obersulzbachtal Valley / Hohe Tauern Mts. / Salzburg / Austria

Photo: Enrico Bonacina, by kind permission of © Domenico Preite

Gadolinite-(Ce) Mineral

Size of the crystal: 0.17 cm

Origin: Washington Pass / Okanogan County / Washington / USA

Photo by kind permission of © Saul Krotki

Gadolinite-(Y) Mineral

Size: 5.3 x 4.8 x 1.9 cm

Origin: Hidra (Hitterø) / Flekkefjord / Vest-Agder / Norway

Photo by kind permission of © www.irocks.com

Gadolinite-(Y)

Size: 1.34 x 1.05 cm
Weight: 9.41 ct
Origin: Norway

Photo by kind permission of © Darlene Cobler