Gadolinite ( mouth. Iterbit ) is a mineral of black (brown-black) color with a greasy, glassy sheen, visible on the edges, sometimes completely opaque. Very rarely found in the form of crystals, usually in the form of a dense mass. Gadolinite is sometimes in the form of an amorphous single-refracting body, then in the form of birefringent, then in the form of an aggregate of one- and birefringent particles.
| Gadolinite | |
|---|---|
 | |
| Formula | ( Ce , La , Nd , Y ) 2 Fe Be 2 Si 2 O 10 |
| Physical properties | |
| Colour | black, brown, brown |
| Shine | oily glassy |
| Transparency | on the edges, sometimes opaque |
| Hardness | 6.5 - 7 |
| Cleavage | easy to obtain from (001) |
| Kink | conchoid, scaly, sometimes uneven |
| Syngonia | monoclinic |
Depending on the prevalence of cerium or yttrium , gadolinite-Ce and gadolinite-Y are distinguished, respectively.
Content
History
Gadolinite was named in 1800 in honor of the Finnish mineralogist - chemist Johan Gadolin , who first isolated rare-earth elements in 1792 [1] . Gadolinium was also named after him. However, gadolinite contains only trace amounts of gadolinium.
Exploring gadolinite, Johan Gadolin missed the opportunity to discover another element - beryllium , mistakenly confusing it with alumina ( aluminum ).
Chemical Composition
The chemical composition of gadolinite is variable - the content of the main components, especially FeO , varies greatly. Mostly gadolinite consists of silicates , cerium , lanthanum , neodymium , yttrium , beryllium and iron . Also, contains thorium , less often - uranium . Gadolinite formulas: ( Ce , La , Nd , Y ) 2 Fe Be 2 Si 2 O 10 or Be 2 Y 2 Fe II ( Si O 4 ) 2 O 2 { Ca , La , Mg , Re , Sc , Th }.
Chemical Properties
Hydrochloric acid decomposes gadolinite with the deposition of gelatinous silicic acid .
Physical Properties
Monoclinic syngony. Hardness - 6.5 - 7, specific gravity 4 - 4.3.
In the flame, some varieties very quickly glow, swell and become white, but do not melt.
Due to the presence of thorium and / or uranium, it is radioactive .
Distribution
Almost always, gadolinite is found in the form of small clusters of black color (in altered samples of dark green) interspersed in granite. Very rare crystals , have a prismatic appearance, sometimes reach gigantic sizes. The weight of some imperfect crystals reaches 80 kg ( Baringer Hill , USA ).
It is distributed in quartz porphyry in Guasso al-Monte ( Varese province) in Italy , in Finbo , Itterby , Falun in Sweden , Cunning in Norway , Harz and Silesia , in the USA , on the Kola Peninsula in Russia .
Mining
It is mined commercially for the production of thorium, uranium and rare earths .
See also
- List of minerals
- Gadolinium
Notes
- β Gadolin, Johann // Brockhaus and Efron Encyclopedic Dictionary : in 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
Links
- Gadolinite in the geological encyclopedia GeoWiki.
- Gadolinite in the database www.mindat.org