Tugtupite
Current inventory:  0 gems
 

  
Tugtupite is named after its discovery locality, Tugtup agtakôrfia, Tunugdliarfik, Greenland.

Discovered in 1957; IMA status: Valid (IMA approved 1962)

Chemistry

Chemical Formula:

Na₄AlBeSi₄O₁₂Cl

Sodium Aluminum Berylium Silicate Chloride

Molecular Weight:

467.74 gm

Composition:

Sodium

19.66 %

Na

26.50 %

Na₂O

Beryllium

1.93 %

Be

5.35 %

BeO

Aluminum

5.77 %

Al

10.90 %

Al₂O₃

Silicon

24.02 %

Si

51.38 %

SIO₂

Chlorine

7.58 %

Cl

7.58 %

Cl

—

 —  %

Cl

-O=Cl₂

Oxygen

41.05 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates

Strunz 8th Ed. ID:

8/J.11-50

Nickel-Strunz 10th Ed. ID:

9.FB.10

9 : SILICATES (Germanates)
F : Tektosilicates without zeolitic H₂O
B : Tektosilicates with additional anions

Related to:

Helvine Group.

Members of Group:

Helvine Group: Danalite, Genthelvite, Helvine, Tugtupite

Varieties:

None

Synonyms:

Helvite, Moonlight Garnet, Tetrahedral Garnet

Crystal Data

Crystallography:

Tetragonal - Disphenoidal

Crystal Habit:

Crystals are short tetragonal prisms with pyramids, sphenoids, and bisphenoids, to 3 mm; fine-grained aggregates, massive.

Twinning:

Penetration twinning produces pseudocubic triplets; pseudotrigonal contact twins with composition planes.

Physical Properties

Cleavage:

Distinct on [101], Fair on [110]

Fracture:

Conchoidal

Tenacity:

Brittle

Moh's Hardness:

4.0

Density:

2.33 (g/cm³)

Luminescence:

Fluorescent; bright orange under LW UV. Phosphorescent red to rose-pink under UV; photochromic, pale colors become deep pink on exposure to sunlight or X-rays.

Radioactivity:

Not Radioactive

Other:

Piezoelectric

Optical Properties

Color:

White, Pink, Crimson, Blue, Green

Transparency:

Opaque, Translucent, Transparent

Luster:

Vitreous to Greasy

Refractive Index:

1.492 - 1.502  Uniaxial ( + ); anomalously Biaxial

Birefringence:

0.0060

Dispersion:

0.012

Pleochroism:

Weak Lilac to weak Red-Orange

Occurances

Geological Setting:

Replaces chkalovite in hydrothermal veins cutting sodalite syenite and syenite (Ilimaussaq intrusion, Greenland); an alteration product in pegmatites in a differentiated alkalic massif (Lovozero massif, Russia).

Common Associations:

Albite, Analcime, Aegirine, Natrolite, Tetranatrolite, Chkalovite, Lithian mica, Epistolite, Niobophyllite, Monazite, Rhabdophane, Gerasimovskite, Nenadkevichite, Beryllite

Common Impurities:

Fe, Ga, Mg, Ca, K, H₂O, S

Type Locality:

Tugtup agtakôrfia, Ilimaussaq complex, Narsaq, Kitaa (West Greenland) Province, Greenland

Year Discovered:

1957

View mineral photos:

Tugtupite Mineral Photos and Locations

More Information

Mindat.org
Webmineral.com

Tugtupite is a rare member of the Helvine Group of minerals that includes Danalite, Genthelvite and Helvine. Tugtupite was discovered in Tugtup agtakôrfia, Tunugdliarfik, Greenland in 1962. It is also known as Reindeer Stone because Tugtup means reindeer. Most material is opaque to translucent and used for cabochons. Transparent material is rarely available and cut into very small faceted gems. These are very rare and usually slightly to moderately included. Tugtupite has an unusual characteristic in that it darkens in color when exposed to UV light and then slowly lightens back up. Tugtupite is also fluorescent exhibiting bright orange under longwave UV light. If you hover your cursor over the Tugtupite picture at the top of this page you will see the Tugtupite gem exhibiting it bright orange color under longwave UV light.

The main sources of Tugtupite are Tasseq Slope, Ilimaussaq complex, Narsaq, Kitaa Province, Greenland; and minor occurances at Kola Peninsula Russia and Mont Saint-Hilaire, Quebec, Canada.
 

  
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