Images
Formula: Ce2Fe2+Be2O2(SiO4)2
Nesosilicate (insular SiO4 groups),
gadolinite subgroup,
gadolinite group,
gadolinite supergroup,
cerium-bearing mineral
Crystal System: Monoclinic
Specific gravity: 4.20 measured
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).
At Fairview, Stove Mountain, El Paso County, Colorado, USA, miarolitic cavities host black gadolinite-Ce
crystals that reach 1 mm and are associated with smoky quartz,
microcline, albite,
ilmenite, green fluorite,
fluocerite and bastnäsite
(R&M 97.5.418).
Back to Minerals