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Formula: (Ca3Ce)Na(NaCa)Ti(Si2O7)2(OF)F2
Sorosilicate (Si2O7 groups), rinkite group of
the seidozerite supergroup, closely related to
mosandrite-(Ce)
Crystal System: Monoclinic
Specific gravity: 3.18 to 3.44 measured, 3.439 calculated
Hardness: 5
Streak: Yellow-white
Colour: Yellowish-brown, yellow; brown
Common impurities: Zr,Th,Y,La,Fe,Mn,Mg,K,H2O
Environments
Plutonic igneous environments
Pegmatites
Localities
At the Saima complex, Kuandian County, Dandong, Liaoning, China, the
nepheline syenite
pegmatite is characterised by rare-earth-element
mineralisation, mainly rinkite-(Ce) and associated alteration minerals. As the most abundant
rare-earth-element-bearing mineral in the pegmatite,
rinkite-(Ce) closely coexists with microcline,
nepheline, natrolite and
calcite. Primary rinkite-(Ce) has undergone multiple episodes of
fluid interactions, and accordingly, from weak to strong, three different mineral assemblages of hydrothermal
alteration can be summarized:
(1) rinkite-(Ce) + secondary
natrolite +/- K-feldspar +/-
minor fluorbritholite-(Ce)
(2) rinkite-(Ce) relics + secondary
natrolite + K-feldspar
+ fluorbritholite-(Ce) + unidentified
calcium-titanium silicate mineral +
fluorite and calcite
(3) pseudomorphs after rinkite-(Ce)
The pseudomorphs can be divided into two groups characterised by
distinct mineral associations:
[1] calcium-bearing strontianite +
fluorbritholite-(Ce) +
natrolite + fluorite +
calcite coexisting with silicate minerals
[2] calcite + fluorite +
fluorbritholite-(Ce) + rinkite-(Ce) relics +/-
calcium-bearing strontianite +/-
ancylite-(Ce) associated with a
calcite matrix
(CM 57.903-924).
The type locality is the Kangerluarsuk Fjord, Ilímaussaq complex, Kujalleq, Greenland.
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