Sugilite
| Sugilite | |
|---|---|
 (size of the sugilite lump 1 cm) |
|
| General and classification | |
| other names |
|
| chemical formula | K [12] Na 2 [9] (Fe 3+ , Mn 3+ , Al) 2 [6] Li 3 [4] [Si 12 O 30] |
|
Mineral class (and possibly department) |
Silicates and germanates - ring silicates (cyclosilicates) |
|
System no. to Strunz and to Dana |
9.CM.05 ( 8th edition : VIII / E.22) 63.02.01a.09 |
| Crystallographic Data | |
| Crystal system | hexagonal |
| Crystal class ; symbol | dihexagonal-dipyramidal; 6 / m 2 / m 2 / m |
| Room group (no.) | P 6 / mcc (No. 192) |
| Lattice parameters | a = 10.01 Å ; c = 14.01 Å |
| Formula units | Z = 2 |
| Physical Properties | |
| Mohs hardness | 5.5 to 6.5 |
| Density (g / cm 3 ) | measured: 2.74 to 2.79; calculated: 2.80 |
| Cleavage | indistinct after {0001} |
| Break ; Tenacity | uneven to scalloped |
| colour | purple, brownish yellow |
| Line color | White |
| transparency | transparent to opaque |
| shine | Glass gloss, matt |
| Crystal optics | |
| Refractive indices |
n ω = 1.610 n ε = 1.607 |
| Birefringence | δ = 0.003 |
| Optical character | uniaxial negative |
| Pleochroism | weak: pink / light pink |
Sugilith (also sugilite ) is a rarely occurring mineral from the mineral class of " silicates and Germanates ". It crystallizes in the hexagonal crystal system with the chemical composition K [12] Na 2 [9] (Fe 3+ , Mn 3+ , Al) 2 [6] Li 3 [4] [Si 12 O 30] , so it is chemically in the idealized form is a potassium - sodium - iron - lithium silicate. Structurally it belongs to the ring silicates . The elements iron, manganese and aluminum indicated in the round brackets can represent each other in the formula ( substitution , diadochie), but are always in the same proportion to the other components of the mineral. The numbers in superscript and surrounded by square brackets indicate the coordination number for the respective element.
Sugilite rarely develops larger crystals , which can then, however, be up to two centimeters in size and whose surfaces have a glass-like sheen . Most of the time, sugilite is found in the form of granular to massive mineral aggregates with a predominantly strong purple to magenta-like color. Brownish-yellow color varieties are also known. However, sugilite leaves a white line on the marking board .
Sugilite is only used as a gemstone .
Etymology and history
Sugilite was first discovered in 1944 by Professor Ken-ichi Sugi on the small island of Iwagi in the Seto Inland Sea , which is part of the Ehime Prefecture of Japan. The mineral was analyzed and described in 1976 by Nobuhide Murakami, Toshio Kato, Yasunori Miúra, Fumitoshi Hirowatari, who named it after its discoverer.
classification
In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the sugilite belonged to the division of " ring silicates (cyclosilicates)", where together with almarudite , armenite , berezanskite , brannockite , chayesite , darapiosit , dusmatovite , eifelite , emeleusite , Faizievite , Poudretteit , Merrihueit , Milarit , Oftedalit , Osumilite , Osumilite- (Mg) , Roedderite , Shibkovite , Sogdianite , Trattnerite , Yagiit and Yakovenchukit- (Y) the " Milarite-Osumilite-Group " with the system no. VIII / E.22 .
The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also classifies sugilite in the section of "ring silicates (cyclosilicates)". This is, however, further subdivided according to the structure of the rings, so that the mineral can be found according to its structure in the sub-section "[Si 6 O 18 ] 12 - six-double rings", where it is found together with almarudite, armenite, berezanskite, brannockite, Chayesite, Darapiosit, Dusmatovit, Eifelit, Friedrichbeckeit , Klöchit , Merrihueit, Milarit, Oftedalit, Osumilith, Osumilith- (Mg), Poudretteit , Roedderit, Shibkovit, Sogdianit, Trattnerit and Yagiit form the unnamed group 9.CM.05 .
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns sugilite to the class of "silicates and germanates", although there it is in the more finely divided division of "ring silicates: condensed rings". Here it is in the "Milarite Osumilith Group (Milarite Osumilith Subgroup)" with the system no. 63.02.01a can be found in the subsection “ Ring Silicates : Condensed, 6-membered Rings ”.
Education and Locations
Sugilite forms hydrothermally as a component of alkaline, aegirin-containing syenites . In addition to aegirine, accompanying minerals ( parageneses ) can include albite , allandite , andradite , apatite , pectolite , quartz , titanite and zirconium .
As a rare mineral formation, sugilite could only be detected at a few sites, whereby so far (as of 2013) around 10 sites are known. In addition to its type locality Iwagi, the mineral is only known in Japan from the “Furumiya” manganese ore mine on Shikoku Island .
The "Wessels Mine" near Hotazel in the manganese ore fields of the Kalahari in South Africa is known for its rich, also crystalline, sugilite finds .
Other previously known sites include the “Woods Mine” near Tamworth and the “Hoskins Mine” near Grenfell in the Australian state of New South Wales, the “Cerchiara Mine” near Borghetto di Vara (Liguria) and Castagnola in the municipality of Vagli di Sotto ( Tuscany) in Italy, the “Poudrette” quarry on Mont Saint-Hilaire in Canada, the “N'Chwaning Mines” near Kuruman and the “AKH49” borehole near Sishen in South Africa and the Dara-i-Pioz glacier ( Darai-Pioz ) in the Alai Mountains in Tajikistan.
Crystal structure
Sugilite crystallizes hexagonally in the space group P 6 / mcc (space group no. 192) with the lattice parameters a = 10.01 Å and c = 14.01 Å as well as 2 formula units per unit cell .
use
Depending on the quality and the play of colors, sugilite is ground into various gemstone shapes and offered either as a table cut , as a cabochon or as a tumbled stone .
High-quality sugilite has bright purple to reddish colors and is always somewhat transparent. Due to the scarcity of the current deposits, the adjacent rock (gray, brown, red, black, ...) is also sold as sugilite. You can recognize good sugiliths by their strong, bright colors. Sugiliths are usually very reddish in lamplight and shine less than in sunlight. When illuminated with white LEDs, the colors of good sugilites "glow" or shine particularly intensely.
Bad material is easy to spot. It often shows only a few and poorly colored portions of sugilite in the bedrock, whereby these sugilite portions are mainly rather reddish. The "radiance" or "glow" of the colors is usually completely absent or is only extremely weak. With some good sugiliths, however, it is often impossible to avoid the fact that a lot of the bedrock is preserved.
Esoteric
In esoteric circles , sugilite is also known under the trade names Luvulith and Royal Azel and is used either as a sidereal pendulum or as an amulet or healing stone with an allegedly harmonizing effect on nerves and brain. However, the latter has not been scientifically proven.
See also
literature
- Nobuhide Murakami, Toshio Kato, Yasunori Miúra, Fumitoshi Hirowatari: Sugilite, a new silicate mineral from Iwagi Islet, Southwest Japan. In: Mineralogical Journal. Volume 8, 1976, pp. 110-121 ( rruff.info PDF; 757.5 kB).
- T. Armbruster, R. Oberänsli: Crystal chemistry of double-ring silicates: Structures of sugilite and brannockite. In: American Mineralogist. Volume 73, 1988, pp. 595-600 ( rruff.info PDF; 1.0 MB).
- Petr Korbel, Milan Novák: Mineral Encyclopedia (= Villager Nature ). Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 231 .
Web links
- Mineral Atlas: Sugilite (Wiki)
- Database-of-Raman-spectroscopy - Sugilite.
- American-Mineralogist-Crystal-Structure-Database - Sugilite.
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 .
- ↑ a b Webmineral - Sugilite.
- ↑ a b c d Sugilite. In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America. 2001 ( handbookofmineralogy.org PDF; 74.2 kB).
- ↑ a b Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 231 .
- ↑ a b c Mindat - Sugilite.
- ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp. 714 (first edition: 1891).
- ↑ Mindat - Number of localities for Sugilite.
- ↑ Mindat - Wessels Mine, Hotazel, Kalahari manganese fields, Northern Cape Province, South Africa and examples of the finds .
- ↑ Find location list for sugilite in the Mineralienatlas and Mindat .
- ^ A b Walter Schumann: Precious stones and gemstones. All species and varieties in the world. 1600 unique pieces . 13th revised and expanded edition. BLV Verlags-GmbH, Munich et al. 2002, ISBN 3-405-16332-3 , p. 266, 281, 283 .
- ↑ realgems.org - Sugilith (milled with picture examples stones)
- ↑ Institute for Gemstone Testing (EPI) - trade names and what they mean (trade names must be entered)