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Formula:
Na15Ca6Fe3Zr3Si(Si25O73)(O,OH,H2O)3(Cl,OH)2
Cyclosilicate (ring silicate), eudialyte group,
zirconium-bearing mineral
Varieties
Eucolite is an optically negative variety of eudialyte
Crystal System: Trigonal
Specific gravity: 2.74 to 3.1 measured
Hardness: 5 to 6
Streak: White to pale pink
Colour: Carmine-red, orange-red, orange, pink, cherry-red, brownish-red, yellowish-brown, brown, yellow, violet, green.
Solubility: Gelatinises with acids (Dana)
Common impurities: K,Mg,Sr,TR,Ti,Nb,Al,F,P,S
Environments
Plutonic igneous environments
Pegmatites
Eudialyte occurs in igneous rocks such as nepheline syenite and
granite, and their associated pegmatites (Webmin, Dana, HOM). It may alter
to catapleiite, zircon,
feldspar, aegirine,
analcime and clay minerals (Dana). Associated minerals include
microcline, nepheline,
aegirine, lamprophyllite,
lorenzenite, murmanite,
arfvedsonite, sodalite,
aenigmatite, rinkite,
lavenite, titanite and titanian
magnetite (HOM).
The type locality is the Kangerluarsuk Fjord, Ilímaussaq complex, Narsaq, Kujalleq, Greenland, Denmark.
At the Palitra pegmatite, Lovozero Massif, Kola Peninsula, Russia, eudialyte is associated with
aegirine, arfvedsonite,
lorenzenite, microcline,
nepheline and villiaumite
(Min Rec 36.5.404).
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