Celsian
| Celsian | |
|---|---|
 |
|
| General and classification | |
| chemical formula | Ba [Al 2 Si 2 O 8 ] |
|
Mineral class (and possibly department) |
Silicates and Germanates - framework silicates (tectosilicates) |
|
System no. to Strunz and to Dana |
9.FA.30 ( 8th edition : VIII / J.06) 76.01.01.04 |
| Crystallographic Data | |
| Crystal system | monoclinic |
| Crystal class ; symbol | monoclinic prismatic; 2 / m |
| Space group | I 2 / c (No. 15, position 6) |
| Lattice parameters |
a = 8.62 Å ; b = 13.08 Å; c = 14.41 Å β = 115.1 ° |
| Formula units | Z = 8 |
| Physical Properties | |
| Mohs hardness | 6 to 6.5 |
| Density (g / cm 3 ) | 3.1 to 3.4 |
| Cleavage | perfect after {001}, good after {010}, indistinct after {110} |
| colour | colorless, white, gray to pale yellow |
| Line color | White |
| transparency | transparent |
| shine | Please complete |
| Crystal optics | |
| Refractive indices |
n α = 1.580 to 1.584 n β = 1.585 to 1.587 n γ = 1.594 to 1.596 |
| Birefringence | δ = 0.014 |
| Optical character | biaxial positive |
| Axis angle | 2V = 86 to 90 ° |
| Pleochroism | not available (colorless) |
Celsian is a rarely occurring barium - Aluminosilicate - mineral from the mineral class of silicates and germanates, more specifically to a framework silicate (tectosilicate) with the chemical composition Ba [Al 2 Si 2 O 8 ]. It crystallizes in the monoclinic crystal system and develops mostly massive forms, but sometimes also short, prismatic to needle-like crystals in the centimeter range.
Celsian is a member of the large group of feldspars and, with Orthoclase as the second terminal link , forms a mixed series whose mixed crystals are called hyalophanes .
Etymology and history
The mineral was first found and described in the Jakobsberg mine in Nordmark / Värmland in Sweden in 1895 . It was named after Anders Celsius (1701–1744), a Swedish astronomer, mathematician and physicist.
classification
In the meantime outdated, but still in use 8th edition of the mineral classification by Strunz of celsian belonged to the mineral class of "silicates and Germanates" and then to the Department of " framework silicates (tectosilicates)" where he collaborated with Buddingtonit , Hyalophane , Kokchetavit , microcline , Orthoclase , Paracelsian , Rubiklin , Sanidin and Slawsonite formed the independent “Buddingtonite-Orthoclase-Slawsonite series” within the group of feldspars .
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 assigns the Celsian to the class of "silicates and Germanates", but there in the now more finely subdivided section of "tectosilicates" without zeolitic H 2 O “. This section is further subdivided according to the possible presence of further anions , so that the mineral can be found according to its composition in the sub-section "Tectosilicates (tectosilicates) without additional anions", where it can be found together with adulara , anorthoclase , buddingtonite, hyalophane, kokchetavite, Mikroklin, Monalbit , Orthoclase, Rubiklin and Sanidin the "feldspar group" with the system no. 9.FA.30 forms.
The systematics of minerals according to Dana , which is mainly used in the English-speaking area , assigns the Celsian to the class of "silicates and Germanates" and there in the department of "framework silicates with Al-Si lattice". Here he is together with Anorthoklas, Filatovit, Hyalophan, Mikroklin, Orthoklas, Rubiklin and Sanidin in the group of "K (Na, Ba) -Feldspar" with the system no. 76.01.01 to be found in the subsection " With Al-Si grid ".
Modifications and varieties
Another naturally occurring modification of this barium aluminosilicate is Paracelsian , which also crystallizes monoclinically, but in a different space group.
The hexagonal modification Hexacelsian , on the other hand, is only stable above 1590 ° C up to the melting point (> 1700 ° C) and has not yet been proven as a natural mineral, but has been produced synthetically.
Education and Locations
Celsian arises through regional or contact metamorphosis in amphibolites rich in manganese or barium and enters paragenesis with barite , cymrite , dolomite , hausmannite , hyalophane , jacobsite , muscovite , paracelsian, quartz , rhodochrosite , rhodonite , rutile , spessartine , taramellite and zoisite .
In addition to its type locality Nordmark / Värmland, it was found in Sweden in Sundsvall in Medelpad and Nyköping in Södermanland .
Worldwide, Celsian has been in New South Wales and Tasmania in Australia ; Lombardy , Piedmont and Sardinia in Italy ; Honshū and Shikoku in Japan ; British Columbia in Canada ; Almaty in Kazakhstan ; Baja California in Mexico ; Otjozondjupa in Namibia ; eastern Siberia in Russia ; and Värmland (type locality) in Sweden ; Canton of Valais in Switzerland ; Moravia in the Czech Republic ; in Scotland and Wales in the United Kingdom (Great Britain and Northern Ireland) and in Alaska , Arizona , California , Nevada and New Jersey in the United States of America .
Crystal structure
Celsian crystallizes in the monoclinic in the space group I 2 / c (space group no. 15, position 6) with the lattice parameters a = 8.62 Å ; b = 13.08 Å; c = 14.41 Å and β = 115.1 ° as well as 8 formula units per unit cell .
See also
Web links
- Mineral Atlas: Celsian (Wiki)
- Mineral data sheet - Celsian (PDF 69 kB)
Individual evidence
- ↑ Webmineral - Celsian (Eng.)
- ^ A b c Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p. 694 .
- ↑ a b Celsian at mindat.org (engl.)
- ↑ Stefan Weiß: The large Lapis mineral directory . 4th edition. Christian Weise Verlag, Munich 2002, ISBN 3-921656-17-6 .
- ↑ Martin Okrusch, Siegfried Matthes: Mineralogie: An introduction to special mineralogy, petrology and deposit science . 7th edition. Springer Verlag, Berlin, Heidelberg, New York 2005, ISBN 3-540-23812-3 , pp. 117 .
- ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 935. Restricted preview in the Google book search
- ↑ Find location list for Celsian at the Mineralienatlas and at Mindat