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Formula: Na6Na2Ti2Na2Ti2(Si2O7)2(PO4)2O4
Sorosilicate (Si2O7 groups), murmanite group,
titanium-bearing mineral
Crystal System: Triclinic
Specific gravity: 2.88 to 3.13 measured, 3.04 calculated
Hardness: 3 to 4
Streak: Light rose-cinnamon
Colour: Dark cinnamon-brown to black, also rose-violet
Common impurities: Zr,Fe,Nb,Ta,Mn,Mg,Ca,Cl,H2O
Environments:
Igneous environments
Pegmatites
Lomonosovite alters to murmanite, and may be replaced by
narsarsukite, neptunite,
mountainite and sometimes bornemanite
(Dana). Associated minerals include nepheline,
albite, pectolite,
lorenzenite, ussingite,
lamprophyllite, eudialyte,
arfvedsonite, villiaumite and
aegirine
(HOM).
Localities
At the Ilímaussaq complex, Narsaq, Kujalleq, Greenland, lomonosovite occurs in fine-grained lavas and in
gabbro near the contact with intrusive
nepheline syenite composed of
arfvedsonite, aegirine,
microcline, albite,
nepheline and eudialyte
(Dana).
At the type locality, Pegmatite No. 65, Chinglusuai River Valley, Lovozersky District, Murmansk Oblast, Russia, lomonosovite
occurs in pegmatites in syenite; associated minerals include sodalite variety
hackmanite, ussingite,
lamprophyllite, eudialyte,
arfvedsonite, microcline,
lorenzenite, aegirine, and sometimes neotocite
variety chinglusuite, nordite,
neptunite, sphalerite and
molybdenite
(AM 35.1092-1093).
At the Palitra pegmatite, Karnasurt mine, Kedykverpakhk Mountain, Lovozersky District, Murmansk Oblast, Russia, lomonosovite
is abundant in the core as crystals to 12 cm long, sometimes associated with vuonnemite.
In the peripheral zones of the pegmatite lomonosovite occurs as lamellae to 5 cm in the centres of large
aegirine spheroids and in aegirine -
eudialyte - lorenzenite aggregates. Rarely,
small bornemanite spherules replace lomonosovite on its contact with
natrosilite
(Minrec 36.5.406).
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