Tugtupit
| Tugtupit | |
|---|---|
 |
|
| General and classification | |
| other names |
|
| chemical formula | Na 4 [Cl | BeAlSi 4 O 12 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates |
|
System no. to Strunz and to Dana |
9.FB.10 ( 8th edition : VIII / J.11) 76.02.03.07 |
| Crystallographic Data | |
| Crystal system | tetragonal |
| Crystal class ; symbol | tetragonal-disphenoidic; 4th |
| Space group | I 4 (No. 82) |
| Lattice parameters | a = 8.64 Å ; c = 8.87 Å |
| Formula units | Z = 2 |
| Twinning | pseudocubic penetration triplets according to (101); pseudotrigonal contact twins according to (10 1 ) and (01 1 ) |
| Physical Properties | |
| Mohs hardness | ≈ 4 |
| Density (g / cm 3 ) | measured: 2.33 (1); calculated: 2.34 to 2.35 |
| Cleavage | clearly after {101}; indistinct after {110} |
| Break ; Tenacity | uneven to scalloped |
| colour | white, pink, carmine, bluish, greenish |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n ω = 1.496 n ε = 1.502 |
| Birefringence | δ = 0.006 |
| Optical character | uniaxial positive (abnormal also biaxial) |
| Other properties | |
| Special features | Fluorescence , phosphorescence , piezoelectricity , photochromism |
Tugtupite , as Berylliumsodalith or reindeer stone known is a rarely occurring mineral from the mineral class of "silicates and Germanates" with the chemical composition Na 4 [Cl | BeAlSi 4 O 12 ] and is therefore chemically seen a sodium - beryllium - aluminum - silicate with additional chlorine ions .
Tugtupite crystallizes in the tetragonal crystal system , but rarely develops crystals in the millimeter range with a glass-like sheen on the surfaces. It is mostly found in the form of granular to massive mineral aggregates up to about 10 cm in size.
In its pure form, tugtupite is colorless and transparent. However, due to multiple light refraction due to lattice construction defects or polycrystalline formation, it can also appear white, with the transparency decreasing accordingly. Through the addition of foreign substances , Tugtupit can also take on a pink, carmine-red, bluish or greenish color.
Etymology and history
European geologists discovered tugtupite in 1957. The Inuit in Greenland had known this stone for centuries. They named Tugtupit after the blood of reindeer ("tuttu"). However, the mineral received its official name in 1962 from his first described H. Sørensen, who it after its type locality Tuttup Attakoorfia (the old spelling Tugtup Agtakôrfia named).
classification
Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the tugtupite belonged to the mineral class of "silicates and germanates" and there to the department of "tectosilicates (tectosilicates), with zeolites ", where together with Bicchulith , Haüyn , Hydrosodalite , Kamaishilite , Lasurit , Nosean , Sodalite and Tsaregorodtsevit the "Sodalite series" with the system no. VIII / J.11 formed.
In contrast , the 9th edition of Strunz's mineral systematics, which has been in force since 2001 and is used by the International Mineralogical Association (IMA), classifies tugtupite under the category of “tectosilicates without zeolitic H 2 O”. This is further subdivided according to the possible presence of additional anions , so that the mineral can be found according to its composition in the sub-section "Tectosilicates (tectosilicates) with additional anions", where it can be found together with Bicchulite, Danalith , Genthelvin , Haüyn, Helvin , Kamaishilith, Lasurit, Nosean, Sodalith and Tsaregorodtsevit the "Sodalith-Danalith-Gruppe" with the system no. 9.FB.10 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns tugtupite to the class of "silicates and germanates" and there in the department of "structural silicates: Al-Si lattice". Here he is in the " sodalite group " with the system no. 76.02.03 within the sub-section “Framework silicates: Al-Si lattices, feldspar representatives and related species”.
Crystal structure
Tugtupite crystallizes tetragonally in space group I 4 (space group no. 82) with the lattice parameters a = 8.64 Å and c = 8.87 Å as well as two formula units per unit cell .
properties
In daylight, the color spectrum of tugtupite ranges from white to pink to a deep red. Bluish stones are also found very rarely. The red color results from small amounts of sulfur in the tugtupite. When a pale tugtupit is exposed to UV light or sunlight, the red intensifies. This deepening of color can last for weeks. In the dark the red fades again ( photochromism ). Tugtupites can also react to heat.
Tugtupite is known for its excellent fluorescence . The mineral glows cherry red under short-wave UV light, and more or less orange under long-wave UV light. Dark red tugtupite from the Kvanefjeld area shows the strongest reaction to UV light. This tugtupite shows no phosphorescence . Pale pink tugtupite from the Taseq region shows a different UV reaction: a weaker red under short-wave UV, salmon-orange under long-wave UV and pink-violet under medium-wave UV. This tugtupite shows a strong, whitish phosphorescence. Stones from other areas of discovery in the Ilímaussaq complex react differently again: a pink-orange under short-wave UV, a very light white under medium-wave UV and orange under long-wave UV, also phosphorescent.
Furthermore, Tugtupit has piezoelectric properties, i.e., similar to quartz , it builds up an electrical voltage with periodically changing, elastic deformation.
The indication of Mohs' hardness is given as 4 or 5.5 to 6, depending on the source.
Education and Locations
Tugtupite is mainly formed in hydrothermal veins of syenite - pegmatites , where it replaces the chkalovite . The occurrence is limited to an 8 × 17 km area in the south of Greenland , the "Ilimmaasaq complex". There are more than 250 different minerals (Greenland: more than 500 minerals, with 77 type localities). On the northern shore of the fjord in Tuttup Attakoorfia: Here is the first Tugtupite 1957 found Tunulliarfik that this nepheline - syenite - Intrusion cuts. The small town of Narsaq is 11 km west of the center of the Ilimmaasaq complex. The area is only sparsely overgrown with low plants, is very weathered and rises from SE to NW. The Ilimmaasaq (1390 m) is the highest point in the complex. The find area can only be reached on foot in the summer months.
Tugtupite is also found in Mont-Saint-Hilaire ( Québec , Canada ) and in the Lovozero massif on the Kola Peninsula in northern Russia . The United States Geological Survey reports that significant amounts of tugtupite have been found in rivers in Nepal.
use
Translucent or transparent, deep red (in daylight) stones from the Kvanefjeld region are processed into gemstones (rings, pendants, etc.). Inuit artists supplement their income by grinding, polishing and then selling the rough stones. Good tugtupites are relatively translucent and have no other visible inclusions of foreign minerals. The best stones are almost transparent, bright red and very sought after by gemstone enthusiasts. However, one must take into account the low Mohs hardness . Tugtupite should therefore not be used in rings that are used every day. Only Greenland can supply the international market with sufficient quantities of valuable, sometimes deep red and very sought-after Tugtupits.
See also
literature
- Petr Korbel, Milan Novák: Encyclopedia of Minerals . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 269 .
Web links
- Mineral Atlas: Tugtupite (Wiki)
- RRUFF Database-of-Raman-spectroscopy - Tugtupite (English)
- American Mineralogist Crystal Structure Database - Tugtupite (English)
- Realgems.org - series of images on raw and cut tugtupites
- Satellite images of the areas of Narsaq and Narsarsuak, with names of sites
Individual evidence
- ↑ a b c d e Hugo Strunz , Ernest H. Nickel : Strunz Mineralogical Tables. Chemical-structural Mineral Classification System . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 699 .
- ↑ a b c d Tugtupite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 69.1 kB )
- ↑ a b c d Mindat - Tugtupite
- ^ A b Walter Schumann: Precious stones and gemstones. All kinds and varieties. 1900 unique pieces . 16th revised edition. BLV Verlag, Munich 2014, ISBN 978-3-8354-1171-5 , pp. 220 .
- ↑ List of localities for tugtupite in the Mineralienatlas and Mindat
- ↑ USGS 2006 Minerals Yearbook - The Mineral Industries of Bhutan and Nepal (PDF; 106 kB)