Ussingite
Current inventory: 0 gems
 

  
Ussingite is named after Niels Viggo Ussing (1864-1911), professor of mineralogy, University of Copenhagen, Denmark.

DDiscovered in 1914; IMA status: Valid (pre-IMA; Grandfathered)

Chemistry

Chemical Formula:

Na₂AlSi₃O₈(OH)

Sodium Aluminum Silicate Hydroxide

Molecular Weight:

302.22 gm

Composition:

Sodium

15.21 %

Na

20.51 %

Na₂O

Aluminum

8.93 %

Al

16.87 %

Al₂O₃

Silicon

27.88 %

Si

59.64 %

SiO₂

Hydrogen

0.33 %

H

2.98 %

H₂O

Oxygen

47.65 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/J.14-10

Nickel-Strunz 10th Ed. ID:

9.EH.20

9 : SILICATES (Germanates)
E : Phyllosilicates
H : Transitional structures between phyllosilicate and other silicate units

Varieties:

None

Synonyms:

ICSD 6265, PDF 28.1037

Crystal Data

Crystallography:

Triclinic - Pinacoidal

Crystal Habit:

Rarely as pseudocubic to tabular crystals, to 1 cm; fine-grained, compact.

Twinning:

Common on [010]

Physical Properties

Cleavage:

Perfect on {110}

Fracture:

Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

6.0 - 7.0

Density:

2.457 - 2.490 (g/cm³)

Luminescence:

None

Radioactivity:

Not Radioactive

Optical Properties

Color:

Pale pink, lilac-blue, or dark violet-red, may be tarnished on the surface; colorless in thin section.

Transparency:

Transparent to Translucent

Luster:

Slightly greasy to vitreous; slightly pearly on cleavage planes.

Refractive Index:

1.503 - 1.545  Biaxial ( + ) 

Birefringence:

0.041

Dispersion:

None

Pleochroism:

None

Occurances

Geological Setting:

A secondary mineral in pegmatites associated with sodalite syenite (Ilímaussaq intrusion, Greenland); in sodalite xenoliths in an intrusive alkalic gabbro-syenite complex (Mont Saint-Hilaire, Canada).

Common Associations:

Microcline, Natrolite, Aegirine (Ilímaussaq intrusion, Greenland); Natrolite, Aegirine, Microcline, Albite, Sodalite (Lovozero massif, Russia); Villiaumite, Lovozerite, Eudialyte, Lueshite, Griceite, Natrophosphate (Mont Saint-Hilaire, Canada).

Common Impurities:

Ca, K, Cl, H₂O, S

Type Locality:

Kangerdluarssuq Firth (Kangerdluarssuk; Kangerdluarsuk), Ilimaussaq complex, Narsaq, Kitaa Province (West Greenland), Greenland

Year Discovered:

1914

View mineral photos:

Ussingite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Ussingite is named after Niels Viggo Ussing (1864-1911), professor of mineralogy, University of Copenhagen, Denmark. It is a rare mineral that is similar in composition to Sodalite but differs from Sodalite by its lack of fluorescence. It is usually found in a fine-grained massive form and is somewhat brittle. The color can range from yellow/tan, pale pink, lilac-blue to a dark violet red. Ussingite is a secondary mineral in pegmatites associated with sodalite syenite. It is most often found associated with Aegirine, Albite, Microcline, Natrolite, and Sodalite.

Ussingite is found in three localities: southern Greenland, on the Kangerdluarssuk Plateau, in the Ilimaussaq intrusion; from a number of places in both the Lovozero and Khibiny massifs, Kola Peninsula, Russia; Mt. Mont Saint-Hilaire, Quebec, Canada. It is most abundant in the Illimaussaq intrusion around the Kangerdlussaq area of southern Greenland.
 

  
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