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Ussingite 
Summary
Ussingite is a silicate mineral with formula Na2AlSi3O8(OH).[4]
| Ussingite | |
|---|---|
 Ussingite from Shkatulka pegmatite, Umbozero mine (Umbozerskii mine), Alluaiv Mt, Lovozero Massif, Kola Peninsula, Murmanskaja Oblast', Northern Region, Russia | |
| General | |
| Category | Phyllosilicate minerals |
| Formula (repeating unit) | Na2AlSi3O8OH |
| IMA symbol | Usg[1] |
| Strunz classification | 9.EH.20 |
| Crystal system | Triclinic |
| Crystal class | Pinacoidal (1) (same H-M symbol) |
| Space group | P1 |
| Identification | |
| Color | pale to medium violet, reddish violet; sometimes barely tinted purple |
| Fracture | irregular/ uneven |
| Tenacity | brittle |
| Mohs scale hardness | 6–7 |
| Luster | sub-vitreous |
| Streak | white |
| Diaphaneity | transparent, translucent |
| References | [2][3] |
It was named for Niels Viggo Ussing (1864–1911), Copenhagen, Denmark.
References edit