Gadolinite-(Ce)

gadolinite-(Ce)

loparite

chevkinite

zircon

Images

Formula: Ce2Fe2+Be2O2(SiO4)2
Nesosilicate (insular SiO4 groups), gadolinite group, cerium-bearing mineral

Specific gravity: 4.20
Hardness: 6½ to 7
Streak: Greenish-grey
Colour: Black
Slightly RADIOACTIVE
Environments

Plutonic igneous environments
Pegmatites

Localities

At the type locality, Buer, Bjørkedalen, Porsgrunn, Vestfold og Telemark, Norway, gadolinite-(Ce) occurs in a syenite pegmatite along a contact between basalt and monzonite (HOM, Webmin), associated with aegirine, pyrochlore, zircon, apatite, titanite, pyrophanite, magnetite, loparite, chevkinite, biotite, microcline, helvine, molybdenite, albite, apophyllite, quartz and calcite (HOM, Mindat).
The primary sequence of crystallisation in this pegmatite is
(1 - earliest) pyrochlore, aegirine, zircon and minor apatite and titanite;
(2) pyrophanite and minor magnetite;
(3) loparite, chevkinite, gadolinite-(Ce) and zircon;
(4) biotite;
(5) microcline.
The later hydrothermal sequence of crystallisation is:
(1) albite and minor helvine, galena and molybdenite;
(2) minor apophyllite, quartz and calcite (AM 63.188-195).

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