Babingtonite

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Babingtonite
Babingtonite-Prehnite-bab01b.jpg
Tabular babingtonite (black) on prehnite (green) from the Hongquizhen quarry, Meigu , Sichuan, China (size: 4.8 cm × 4.2 cm × 2.8 cm)
General and classification
chemical formula
  • Ca 2 Fe 2+ Fe 3+ [Si 5 O 14 OH]
  • Ca 2 (Fe 2+ , Mn) Fe 3+ [Si 5 O 14 OH]
Mineral class
(and possibly department) 		Silicates and germanates - chain and band silicates
System no. to Strunz
and to Dana 		9.DK.05 ( 8th edition : VIII / F.27)
65.04.01.02
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triclinic pinacoidal; 1
Space group P 1 (No. 2)Template: room group / 2
Lattice parameters a  = 7.469  Å ; b  = 12.161 Å; c  = 6.675 Å,
α  = 86.09 °; β  = 93.94 °; γ  = 112.21 °
Formula units Z  = 2
Physical Properties
Mohs hardness 5.5 to 6
Density (g / cm 3 ) measured: 3.34 to 3.37; calculated: 3.26
Cleavage perfect according to {001}, good according to {010} and {100}
Break ; Tenacity uneven; brittle
colour brown to black
Line color greenish gray
transparency opaque to slightly translucent
shine Glass gloss
Crystal optics
Refractive indices n α  = 1.700
n β  = 1.710
n γ  = 1.725
Birefringence δ = 0.025
Optical character biaxial negative
Axis angle 2V = measured: 50 °; calculated: 76 °
Pleochroism very strong: X = dark green; Y = brown purple; Z = light to dark brown

Babingtonite is a rather seldom occurring mineral from the mineral class of " silicates and germanates ". It crystallizes in the triclinic crystal system with the idealized chemical composition of Ca 2 Fe 2+ Fe 3+ [Si 5 O 14 OH], that is a calcium - iron silicate with additional hydroxide . Structurally, babingtonite is one of the chain and band silicates .

Since babingtonite forms a mixed crystal row with manganese babingtonite (Ca 2 Mn 2+ Fe 3+ [Si 5 O 14 OH]) , the formula for the iron-rich babingtonite is occasionally also used with Ca 2 (Fe 2+ , Mn) Fe 3+ [Si 5 O 14 OH]. The elements bivalent iron and manganese indicated in the round brackets can represent each other in the formula ( substitution , diadochy), but are always in the same proportion to the other components of the mineral.

Babingtonite mostly develops tabular to short columnar crystals or radial mineral aggregates of brown to black color with greenish-gray streak color . The surfaces of the opaque to slightly translucent crystals have a glass-like sheen . With a Mohs hardness of 5.5 to 6, babingtonite is one of the medium-hard minerals which, like the reference mineral orthoclase (6), can be scratched with a steel file.

Etymology and history

Babingtonite was first discovered in the area of Arendal in the Norwegian Fylke Aust-Agder and described in 1824 by Armand Lévy , who named the mineral after the British physician and mineralogist William Babington .

classification

In the outdated but still partially in use 8th edition of the mineral classification by Strunz of Babingtonit belonged to the department of "chain silicates and band silicates (inosilicates)" where he collaborated with Inesit , Lithiomarsturit , Manganbabingtonit , Marsturit , Nambulit , Natronambulit , Rhodonit , Santaclarait and Scandiobabingtonit the "Rhodonite series" with the system no. VIII / F.27 .

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 babingtonite in the category of “chain silicates and band silicates (inosilicates)”. This is, however, further subdivided according to the structure of the chains, so that the mineral can be found according to its structure in the subsection “Chain and band silicates with 5-periodic single chains, Si 5 O 15 ”, where it can be found together with fowlerite , lithiomarsturite, manganese babingtonite , Marsturit, Nambulit, Natronambulit, Rhodonit and Scandiobabingtonit the "Rhodonitgruppe" with the system no. 9.DK.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Babingtonite to the “chain silicate minerals” department. Here it is also in the "Rhodonite group" with the system no. 65.04.01 to be found in the sub-section " Chain Silicates : Simple unbranched chains, W = 1 with chains P = 5 ".

Crystal structure

Babingtonite crystallizes triclinically in the space group P 1 (space group  no.2 ) with the lattice parameters a  = 7.469  Å , b = 12.161 Å, c  = 6.675 Å, α = 86.09 °, β = 93.94 ° and γ = 112 , 21 ° and two formula units per unit cell . Template: room group / 2

properties

In front of the soldering tube , babingtonite easily melts into a magnetic bead.

Education and Locations

Column babingtonite from the Hongquizhen quarry, Meigu , Sichuan, China (size: 5.4 cm × 4.6 cm × 3.6 cm)
Babingtonite (black) on prehnite (green) from Qiaojia , Yunnan, China (size: 71 mm × 55 mm)
Weathered, blue-gray babingtonite from the Prospect Park quarry (New Jersey) , USA ( total size of the sample: 4.7 cm × 3.6 cm × 1.6 cm)

Babingtonite forms hydrothermally granitic pegmatites and diorites , but also in cavities in mafic volcanic rocks , gneisses and skarns . It is often found in paragenesis with prehnite , but is also associated with albite , calcite , epidote , hornblende , orthoclase , quartz and various garnets and zeolites .

As a rather rare mineral formation, babingtonite can sometimes be abundant at various sites, but overall it is not very common. So far (as of 2013) around 160 sites are known. In addition to its Arendal type , the mineral was also found in Norway at Konnerud ( Drammen municipality ) in Buskerud, Sølsnes , Tafjord and Stranda in Møre og Romsdal, Tiltvika ( Hamarøy municipality ) in Nordland, Framruste ( Skjåk municipality ) in Oppland, Fjaler in Sogn og Fjordane, Oppdal in Sør-Trøndelag, Kragerø in Telemark and Ramnes ( Re municipality ) in Vestfold.

In Germany Babintonite could so far at the quarry "Artenberg" near Steinach (Ortenaukreis) and near Malsburg-Marzell in Baden-Württemberg, in the granodiorite quarries near Stützersdorf ( Tittling ) in Bavaria, at Niederscheld and Bornberg Seelbach (Herborn) in Hesse, im Andesite quarry near Kreimbach-Kaulbach in Rhineland-Palatinate and in the Nesselgrund quarry near Schnellbach (Floh-Seligenthal) in Thuringia.

In Austria, the mineral was found in the Seebachtal in the Ankogel group and on the Großer Speikkogel in the Koralpe in Carinthia and on the Krummer See near St. Leonhard in the Pitztal in Tyrol.

The only known site in Switzerland so far is a gneiss quarry in the municipality of Arvigo in the canton of Graubünden.

Other locations include the Antarctic, Australia, China, Canada, Columbia, the Czech Republic, France, Iceland, India, Italy, Japan, Namibia, New Zealand, Poland, Romania, Russia, Sweden, Spain, the Ukraine and the United States of America (USA).

See also

literature

  • Armand Lévy : Account of a new mineral substance . In: The Annals of Philosophy . tape 7 , 1824, p. 275–277 ( rruff.info [PDF; 295 kB ; accessed on July 27, 2017]).
  • Petr Korbel, Milan Novák: Mineral Encyclopedia (=  Villager Nature ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 245 .

Web links

Commons : Babingtonite  - collection of images, videos and audio files

Individual evidence

  1. ↑ 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.  541 .
  2. ^ A b 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.  647 .
  3. ↑ a b c T. Armbruster : Cation distribution in Mg, Mn-bearing babingtonite from Arvigo, Val Calanca, Grisons, Switzerland . In: Swiss mineralogical and petrographic messages . tape  80 , no. 3 , 2000, pp. 279–284 ( available online at e-periodica.ch [accessed on July 27, 2017]).
  4. ↑ a b Babingtonite . 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; 72  kB ]).
  5. ↑ Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 6th completely revised and supplemented edition. Weise, Munich 2014, ISBN 978-3-921656-80-8 .
  6. ↑ a b c d Mindat - Babingtonite
  7. ^ IMA / CNMNC List of Minerals; May 2017 (PDF 1.66)
  8. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  734 (first edition: 1891).
  9. ↑ Mindat - Number of locations for babingtonite
  10. ↑ Find location list for Babingtonite in the Mineralienatlas and Mindat