Ussingite , Vuonnemite Locality: Shkatulka pegmatite, Umbozero mine (Umbozerskii mine), Alluaiv Mt, Lovozero Massif, Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia Original description: A 3.9 by 2.7 cms mass of lilac Ussingite with some yellowish Vuonnemite. JSS specimen and photo. — Photo: John Sobolewski (JSS) · CC BY 3.0
Ussingite
Ussingite is a silicate mineral with formula Na2AlSi3O8(OH). It was named for Niels Viggo Ussing (1864–1911), Copenhagen, Denmark.
Intro adapted from Wikipedia (CC BY-SA).
Ussingite is an IMA-recognized mineral species in the silicate class, with the chemical formula Na₂AlSi₃O₈(OH).
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 6–7; specific gravity 2.46–2.49; White streak; Slightly greasy to vitreous; slightly pearly on cleavage planes luster; optically biaxial.
IMA symbol Usg, grandfathered status — known before the IMA’s founding, named in 1915.
Found as a secondary mineral in pegmatites in association with sodalite syenite (Il¶³maussaq intrusion, Greenland); in sodalite xenoliths in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).
It is found associated with Microcline, natrolite, aegirine (Il¶³maussaq intrusion, Greenland); natrolite, aegirine, microcline, albite, sodalite (Lovozero massif, Russia); villiaumite.
The name refers to Professor Niels Vigo Ussing (1864–1911), of Copenhagen, Denmark.