Images
Formula: CaCe(CO3)2F
Anhydrous carbonate, synchysite group,
cerium-bearing mineral
Crystal system:
Specific gravity: 3.9
Hardness: 4½
Streak: White
Colour: Grey, grey-yellow, orange-yellow, brown, beige, light green, white
Solubility: Readily soluble in acids
Environments:
Plutonic igneous environments
Pegmatites
Carbonatites
Synchysite-(Ce) is best known from alpine fissure-type veins in
granite
and alkalic syenite, where it is typically accompanied by other
rare earth minerals and
quartz, albite, the TiO2
paramorphs and
chlorite. It is found with
parisite in rare earth-bearing
pegmatites and it also occurs in
carbonatites
(Webmin, HOM, MW).
Localities
At the Francon quarry, Montreal, Quebec, Canada, synchysite-(Ce) is the commonest of the rare-earth minerals
found in the quarry,
but still it is very rare. Associated minerals include quartz,
fluorite, dawsonite,
marcasite, pyrite,
mordenite, calcite,
celestine and baryte
(Minrec 37.1.47 ).
Synchysite-(Ce) from the Francon
Quarry - Image
At its type locality, the Narssârssuk pegmatite, Narsaarsuk Plateau, Igaliku, Kujalleq, Greenland, Denmark,
synchysite-(Ce) occurs
in a syenite pegmatite associated with
astrophyllite, catapleiite,
neptunite, epididymite,
elpidite, cordylite-(Ce),
fluorite, rhodochrosite,
polylithionite, aegirine,
microcline and albite
(HOM, Dana, Mindat).
At the Trimouns quarry, France, synchysite-(Ce) is commonly associated with
allanite,
and rarely with xenotime. It may form syntaxic intergrowths with
bastnäsite
(MinRec 35.3.242).
Synchysite-(Ce) from the Trimouns Quarry -
Image
At the Monte Cervandone area, Devero Alp, Baceno, Verbano-Cusio-Ossola Province, Piedmont, Italy,
synchysite-(Ce) is
fairly common, especially in clefts on the slopes of Monte Cervandone; good finds have also been made around the
Gischihorn and Helsenhorn. Unaltered synchysite-(Ce) crystals up to 1 cm are yellow to orange, medium brown
and red-brown; they are pseudohexagonal and barrel-shaped, with stepped sides and strong cleavage.
Pseudomorphs and partial
pseudomorphs of
gasparite-(Ce) after synchysite-(Ce) are also known
(MinRec 56.3.318).
Synchysite-(Ce) from the Monte Cervandone area -
Image
At the Khibiny massif, Russia, synchysite-(Ce) is associated with
ewaldite,
belovite-(Ce), fluorite,
nenadkevichite, ancylite-(Ce),
kukharenkoite-(Ce),
mckelveyite-(Y),
burbankite, calcite,
baryte and orthoclase
(HOM).
Synchysite-(Ce) from the Khibiny Massif -
Image
At Piz Blas, Val Naps, Graudunden, Switzerland, synchysite-(Ce) occurs with
gadolinite,
K-feldspar variety adularia and xenotime in
alpine veins
(Dana).
At Cwmorthin Quarry, Blaenau Ffestiniog, Gwynedd, Wales, UK, synchysite-(Ce) is rare, but a small number of
specimens have
been recovered from alpine fissure-type veins hosted by banded tuff -
turbidite. Associated minerals include
quartz, anatase and
xenotime
(MW).
Synchysite-(Ce) from the Cwmorthin Quarry -
Image
At Gloddfa Ganol Quarry, Blaenau Ffestiniog, Gwynedd, Wales, UK, synchysite-(Ce) is very rare, occurring in
alpine fissure-type
quartz veins and, with albite and
anatase, in occasional blocks of vuggy brecciated
slate; it is often sparingly coated in microscopic crystals of
pyrite
(MW).
Synchysite-(Ce) from the Gloddfa Ganol Quarry -
Image
At Manod Quarry, Blaenau Ffestiniog, Gwynedd, Wales, UK, synchysite-(Ce) occurs in association with
quartz and albite in alpine
fissure-type veins cutting
an altered intermediate intrusive rock
(MW).
Synchysite-(Ce) from the Manod Quarry -
Image
At Tanygrisiau Station, Blaenau Ffestiniog, Gwynedd, Wales, UK, synchysite-(Ce) was found as a very rare
late-stage mineral in
the alpine fissure-type veins that were exposed by blasting in the mid-1970s. Associated minerals included
quartz, albite,
anatase and clinochlore
(MW).
At the Dolyhir Quarry, Old Radnor, Powys, Wales, UK, synchysite-(Ce) has been found in alpine-type fractures cutting
shale immediately below an unconformity
(MW).
Synshysite-(Ce) from the Dolyhir Quarry -
Image
At the Henry pegmatite, Cotopaxi, Colorado, USA, synchysite-(Ce) and and
synchysite-(Y) are associated
with kainosite-(Y)
(Dana,AM 47.337-343).
At Quincy, Massachusetts, USA, synchysite-(Ce) occurs with parisite
(Dana).
Synchysite-(Ce) from Quincy -
Image
The Scrub Oak Mine, Mine Hill Borough, Morris county, New Jersey, USA, synchysite-(Ce) occurs intimately
intergrown with quartz,
xenotime, bastnäsite and
hematite
(Dana).
Back to Minerals