Analcime
| Analcime | |
|---|---|
 (size 4.3 cm × 4.1 cm × 3 cm) |
|
| General and classification | |
| chemical formula | Na [AlSi 2 O 6 ] • H 2 O |
|
Mineral class (and possibly department) |
Silicates and Germanates - framework silicates |
|
System no. to Strunz and to Dana |
9.GB.05 ( 8th edition : VIII / J.27) 77.01.01.01 |
| Similar minerals | Faujasite , leucite , pollucite |
| Crystallographic Data | |
| Crystal system | different depending on the polymorph, but mostly cubic (see crystal structure ) |
| Crystal class ; symbol | cubic hexakisoctahedral; 4 / m 3 2 / m |
| Space group | see crystal structure |
| Lattice parameters | see crystal structure |
| Formula units | Z = 16 |
| Frequent crystal faces | often {211}, more rarely combinations of {100} and {211} |
| Twinning | Polysynthetic according to {001}, {110} |
| Physical Properties | |
| Mohs hardness | 5 to 5.5 |
| Density (g / cm 3 ) | measured: 2.24 to 2.29; calculated: 2.271 |
| Cleavage | very indistinct after {001} |
| Break ; Tenacity | slightly mussel-like; brittle |
| colour | colorless, white, reddish, yellowish |
| Line color | White |
| transparency | transparent to translucent |
| shine | Glass gloss |
| Crystal optics | |
| Refractive indices |
n α = 1.479 to 1.493 n γ = 1.480 to 1.494 |
| Refractive index | n = 1.479 to 1.493 |
| Birefringence | isotropic or δ = 0.001 |
| Optical character | isotropic or anomalous biaxial negative |
| Axis angle | 2V = 0 to 85 ° |
Analcime is a common mineral of the zeolite group within the mineral class of " silicates and germanates " with the chemical composition Na [AlSi 2 O 6 ] · H 2 O and is therefore chemically seen a hydrous sodium - aluminosilicate .
Analcime crystallizes in the cubic , tetragonal , orthorhombic or monoclinic crystal system depending on its polymorphic formation . Idiomorphic analcime is very similar in its crystal form to leucite , which means that it usually develops perfectly icositetrahedral crystals with a glass-like sheen on the surfaces. Analcime also occurs in the form of granular to massive mineral aggregates .
In its pure form, analcime is clear, colorless. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also appear white and take on a reddish or yellowish color due to foreign admixtures. His line color , however, is always white.
With a Mohs hardness of 5 to 5.5, analcime, like the reference minerals apatite or manganese, is one of the medium-hard minerals that can just be scratched with a knife or with a steel file .
Etymology and history
The word analcim is derived from the Greek ἀναλκής analkis , which means something like weak or powerless and indicates the weak electrostatic chargeability of this material when rubbed.
Analcime was first found on the Cyclops Islands off the east coast of Sicily in Italy and described in 1784 by Déodat Gratet de Dolomieu . The name of the mineral, which is still valid today, was not given until 1797 by René-Just Haüy .
classification
Already in the outdated but still in use 8th edition of the mineral classification by Strunz of analcime belonged to the mineral class of "silicates and Germanates" and then to the Department of " framework silicates (tectosilicates), with zeolites", where he together with faujasite Ca , faujasite -Mg , Faujasit-Na , Paulingit-Ca , Paulingit-K , Pollucit and Wairakit the subgroup of "Cube Zeolites II" with the system no. VIII / J.27 within the " zeolite group ".
The valid since 2001 and by the International Mineralogical Association used (IMA) 9th edition of Strunz'schen systematic mineral assigns the Analcim into the already finely subdivided department of the " framework silicates (tectosilicates) with zeolitic H 2 O; Family of zeolites ”. This is further subdivided according to the structure of the framework, so that the mineral, according to its structure, can be found in the sub-section "Chains of simply connected rings of four", where it is named after the "analcime group" with the system no. 9.GB.05 and the other members ammonioleucite , hsianghualite , leucite , lithosite , pollucite and wairakite.
The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns analcime to the class of "silicates and germanates" and there in the department of "structural silicates: zeolite group". Here it is together with Hsianghualith, Laumontit, Pollucit and Wairakit in the group "Analcim and allied species" with the system no. 77.01.01 to be found in the sub-section of " Real Zeolites ".
Chemism
The chemical composition of analcime is predominantly pure, which means that only a few substitutions are known to date . Occasionally up to 5.5% sodium (Na) can be replaced by potassium (K). Small additions of calcium (Ca) and magnesium (Mg) were also observed. Analcime can contain up to 8.2% H 2 O.
Crystal structure
Analcime forms different polymorphs which, however, are topologically identical and only differ in the degree of arrangement of the aluminum and silicon ions , albeit with decreasing symmetry:
- Analcime-1C crystallizes cubically in the space group Ia 3 d (space group no. 230) with the lattice parameter a = 13.73 Å and 16 formula units per unit cell .
- Analcime-1Q crystallizes tetragonally in the space group I 4 1 / acd (No. 142) with the lattice parameters a = 13.72 Å and c = 13.73 Å and 16 formula units per unit cell.
- Analcime-1O crystallizes orthorhombically in the space group Ibca (No. 73) with the lattice parameters a = 13.73 Å; b = 13.71 Å and c = 13.74 Å as well as 16 formula units per unit cell.
- Analcim-1M crystallizes monoclinically in the space group I 2 / a (No. 15, position 3) with the lattice parameters a = 13.69 Å; b = 13.68 Å; c = 13.67 Å and β = 90.4 ° and 16 formula units per unit cell.
The crystal structure is very similar to leucite and consists of [SiO 4 ] and [AlO 4 ] tetrahedra with 6-, 8- and 12-fold rings that form channels parallel to the 3-fold axes. The water of crystallization and the sodium ions (Na + ) are located in these non-overlapping channels . Na + can, however, be partially replaced ( substituted ) by potassium (K + ) or calcium ions (Ca 2+ ) , the latter causing a valence equalization of Si 4+ by Al 3+ .
properties
The water of crystallization contained in the analcime structure can be easily driven off by heating , whereby the crystals become cloudy. Analcime can be completely dissolved in hydrochloric acid (HCl).
Education and Locations
(size: 3.0 x 2.0 cm)
Analcime forms mainly in the cavities of intermediate and basic plutonites and volcanites , and as a pseudomorphic conversion product of leucite . Furthermore, analcime can also crystallize out directly from an alkali-rich melt . Besides other zeolites, accompanying minerals include calcite , glauconite , prehnite and quartz .
As a frequent mineral formation, analcime can be found in many localities, with around 1,700 localities known to date (as of 2017). In addition to its type locality on the Cyclops Islands, the mineral was also found in Italy in several places in the regions of Campania , Emilia-Romagna , Latium , Liguria , Piedmont , Sardinia , Trentino-South Tyrol , Tuscany and Veneto as well as near Tiriolo in Calabria; Lesina in Apulia; Palagonia in Sicily and Orvieto in Umbria.
The Nidym , a tributary of the Lower Tunguska in Russia, where well-formed crystals of up to 30 cm in size have been found, is also worth mentioning due to the unusual finds of analcima .
In Germany, analcim was used in the Black Forest , at Höwenegg , near Oberbergen and Neckarelz in Baden-Württemberg; in several places in Franconia and the Upper Palatinate as well as in Bad Hindelang in Bavaria; in many places in the Odenwald from Baden-Württemberg to Hesse; near Dillenburg , Rupsroth , Allendorf (Greifenstein) , Wehrda (Marburg) and Vogelsberg in Hesse; near Alfeld (Leine) , apprenticeship , Adelebsen , Peine and in the Harz in Lower Saxony; in the Sauerland and in the Siebengebirge in North Rhine-Westphalia; many places in the Eifel as well as in the Westerwald , near Niederkirchen and Wolfstein in Rhineland-Palatinate; near Hammerunterwiesenthal in the Saxon Ore Mountains and Eckernförde in Schleswig-Holstein; Schnellbach / Floh-Seligenthal found in Thuringia.
In Austria, the mineral occurred mainly in the regions of Burgenland , Carinthia and Styria and near Persenbeug-Gottsdorf in Lower Austria.
In Switzerland, analcim has so far been found near Tinizong-Rona in the canton of Graubünden and on the Gorner glacier near Zermatt in the canton of Valais.
Other locations include Algeria , Angola , Antarctica , Argentina , Armenia , Azerbaijan , Australia , Belgium , Bolivia , Brazil , Bulgaria , Chile , China , Costa Rica , Denmark , Ecuador , Fiji , Finland , France , French Polynesia and the French Kerguelen , Greece , Greenland , Guam , Guatemala , Guinea , India , Iceland , Israel , Japan , Canada , Kazakhstan , Kyrgyzstan , Cuba , Libya , Madagascar , Morocco , Mexico , Namibia , New Zealand , Norway , Papua New Guinea , Paraguay , Peru , Poland , Portugal , Réunion , Romania , other places in Russia , Sweden , Serbia , Slovakia , Spain , South Africa , South Korea , Tajikistan , Czech Republic , Turkey , Uganda , Ukraine , Hungary , the United Kingdom (Great Britain), the United United States of America (USA) and Cyprus .
Analcime could also be detected in rock samples from the Mid-Atlantic Ridge and Central Indian Ridge .
See also
literature
- René-Just Haüy : Analcime, c'est-à-dire, sans vigueur . In: Journal des Mines . tape 5 , 1797, pp. 278–279 ( rruff.info [PDF; 108 kB ; accessed on December 25, 2017]).
- René-Just Haüy : Traité de minéralogie, par le cen . tape 3 . Chez Louis, Paris 1801, p. 183–186 ( limited preview in Google Book search).
Web links
- Mineral Atlas: Analcim (Wiki)
- Webmineral - Analcime (English)
- RRUFF Database-of-Raman-spectroscopy - Analcime (English)
- American-Mineralogist-Crystal-Structure-Database - Analcime (English)
Individual evidence
- ↑ a b c d e f g h 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. 702-703 .
- ^ A b Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp. 856-859 .
- ↑ a b c d e f g Analcime . 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; 75 kB ; accessed on December 25, 2017]).
- ↑ a b c d Mindat - Analcime (English)
- ↑ René-Just Haüy : Analcime, c'est-à-dire, sans vigueur . In: Journal des Mines . tape 5 , 1797, pp. 278–279 ( rruff.info [PDF; 108 kB ; accessed on December 25, 2017]).
- ↑ a b Hans Jürgen Rösler : Textbook of Mineralogy . 4th revised and expanded edition. German publishing house for basic industry (VEB), Leipzig 1987, ISBN 3-342-00288-3 , p. 615 .
- ↑ Martin Okrusch, Siegfried Matthes: Mineralogie. An introduction to special mineralogy, petrology and geology . 7th, completely revised and updated edition. Springer, Berlin [a. a.] 2005, ISBN 3-540-23812-3 , pp. 127 .
- ↑ Petr Korbel, Milan Novák: Mineral Encyclopedia (= Dörfler Natur ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 271 .
- ↑ a b List of locations for analcime in the Mineralienatlas and in Mindat - Localities for Analcime