Lomonosovite

lomonosovite

nordite

lorenzenite

ussingite

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Formula: Na6Na2Ti2Na2Ti2(Si2O7)2(PO4)2O4
Sorosilicate (Si2O7 groups), murmanite group
Specific gravity: 3.12 to 3.15
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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