Catapleiite

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Catapleiite
Catapleiite-20223.jpg
Catapleiite from the Poudrette quarry, Mont Saint-Hilaire , Québec, Canada (size: 3.6 cm × 2.1 cm × 0.4 cm)
General and classification
other names
  • Catapleit
  • Natron catapleit
chemical formula Na 2 Zr [Si 3 O 9 ] • 2H 2 O
Mineral class
(and possibly department)
Silicates and germanates - ring silicates (cyclosilicates)
System no. to Strunz
and to Dana
9.CA.15 ( 8th edition : VIII / E.04)
0259.02.02.01
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group I 2 / c (No. 15, position 6)Template: room group / 15.6
Lattice parameters a  = 12.78  Å ; b  = 7.42 Å; c  = 20.16 Å
β  = 90.4 °
Formula units Z  = 8
Twinning polysynthetic twins at 30 °, 60 ° and 90 °
Physical Properties
Mohs hardness 5.5 to 6
Density (g / cm 3 ) measured: 2.65 to 2.9; calculated: [2.77]
Cleavage perfect according to {100}, imperfect according to {101} and {102}
Break ; Tenacity clamshell; brittle
colour colorless, white, light yellow to yellowish brown, brown, pink to purple, blue-gray, yellowish red to flesh red
Line color white to light yellow
transparency transparent to opaque
shine weak glass gloss, matt
Crystal optics
Refractive indices n α  = 1.591
n β  = 1.592
n γ  = 1.627
Birefringence δ = 0.036
Optical character biaxial positive
Axis angle 2V = 40 ° (measured)

Katapleiite is a relatively rare mineral from the mineral class of "silicates and germanates". It crystallizes in the monoclinic crystal system with the chemical composition Na 2 Zr [Si 3 O 9 ] · 2H 2 O and is therefore chemically a water-containing sodium - zirconium - silicate . Structurally, catapleiite belongs to the ring silicates (cyclosilicates).

Catapleiite develops thin-tabular, pseudo- hexagonal crystals and twins up to about 15 cm in size, which are usually connected to rosette-shaped or leafy to platy mineral aggregates . In its pure form, catapleiite is colorless and transparent. However, due to multiple refraction due to lattice construction defects or polycrystalline formation, it can also appear white and due to foreign admixtures a light yellow to yellowish brown, brown, pink to violet or blue-gray and due to mixed crystal formation with calciocatapleiite (CaZr [Si 3 O 9 ] · 2H 2 O) a yellowish red to flesh-red color, with the transparency decreasing accordingly. The streak color of the mineral, however, is always white to light yellow. Fresh catapleiite crystal samples show a weak glass luster on the surfaces, but these become matt over time due to weathering.

Etymology and history

The mineral name is an allusion to the fact that catapleiite is often found in the company of many other rare minerals and is composed of the ancient Greek words κατα [kata] for with and πλείων (shortened πλεί) [plëi] for many with what is common in mineralogy Appendix -it for the mineral.

The mineral was first discovered on the island of Låven (also Skådön, Lamö or Lamanskjaer) in the Langesundsfjord in the Norwegian province of Vestfold and described in 1950 by PH Weibye, NJ Berlin, KA Sjogren and JB Borck.

In various mineralogical literatures, the mineral can also be found under the name Katapleit , which, however, is neither etymologically correct nor corresponds to the original name given by the first description.

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the catapleiite belonged to the mineral class of "silicates and germanates" and there to the department of "ring silicates (cyclosilicates)", where it was named after the "catapleiite group" with the system -No. VIII / E.04 and the other members Calciokatapleiit and Moskvinit- (Y) .

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 the catapleiit in the category of "ring silicates". However, this is further subdivided according to the ring structure and the possible presence of additional anions , so that the mineral can be found in the subdivision "[Si 3 O 9 ] 6− triple single rings without island-like, complex anions", depending on its composition only together with Calciokatapleiit the "Katapleiitgruppe" with the system no. 9.CA.15 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the catapleiit to the class of "silicates and Germanates" and there in the department of "ring silicates: triple rings". Here he is together with Calciokatapleiit, Gaidonnayit , Georgechaoit , Loudounit and Bobtraillit in the " Katapleiitgruppe " with the system no. 59.02.02 to be found in the subsection "Ring Silicates: Water-Containing Triple Rings".

Crystal structure

Catapleiite crystallizes dimorphically with Gaidonnayite in the monoclinic crystal system in the space group I 2 / c (space group no. 15, position 6) with the lattice parameters a  = 12.78  Å ; b  = 7.42 Å; c  = 20.16 Å and β = 90.4 ° and 8 formula units per unit cell . Template: room group / 15.6

properties

Chemical properties

In front of the soldering tube , catapleiite is easy to melt, and acids (including HCl ) quickly break down the mineral in powdered form.

Physical Properties

With a Mohs hardness of 5.5 to 6, catapleiite is one of the medium-hard minerals that, like the reference mineral orthoclase (Mohs hardness 6), can be scratched with a steel file .

The mineral shows a perfect cleavage after the base {100}. However, its fracture behavior is as brittle as quartz or glass with fracture surfaces that resemble the round imprint of mussels.

Education and Locations

Katapleiit (brownish white) and aegirine (black) from Narsaarsuk ( Narssârssuk ), Kitaa , Greenland (size: 2.8 cm × 2.2 cm × 1.4 cm)
Catapleiite (cream-colored) and natrolite (white) from the Poudrette quarry, Mont Saint-Hilaire, Québec, Canada (diameter of the catapleiite rosette: approx. 12 mm)

Catapleiite forms in volcanic deep rocks ( plutonites ) such as syenites and nepheline syenites, but also magmatic in pegmatites , where it is usually formed by metasomatic conversion of eudialyte . As Begleitminerale occur among other Aegirin , analcime , Astrophyllit , Epididymit , Låvenit , Leukophan (it), natrolite , Rinkit , sodalite and zircon on.

Catapleiite is one of the relatively rare mineral formations that may be abundant at various sites, but are generally not very common. So far (as of 2015) there are around 120 sites. In addition to its type locality Låven and many other places in the municipality of Larvik , the mineral was also found in Norway in the municipality of Sandefjord in the province of Vestfold and in the municipality of Porsgrunn in the province of Telemark.

The largest known crystals with a diameter of up to 15 cm were discovered at Mont Saint-Hilaire in the southwest of the Canadian province of Québec , but some locations for catapleiite are also known in the provinces of Newfoundland and Labrador as well as in British Columbia in western Canada.

Crystals up to 3 cm in size are known from Mount Yukspor on the Russian Kola Peninsula .

In Europe, catapleiite is only known from Ödeshög in Östergötland and Norra Kärr in the province of Jönköpingslän in Sweden.

Other locations are among others in Brazil, China, Greenland, Guinea, Kyrgyzstan, Libya, Madagascar, Morocco, Namibia, Sweden, South Africa and in various states of the USA (Arkansas, Montana, New Mexico, Virginia, Wisconsin).

Use as a gem stone

As a gemstone , catapleiite has only been on the market for a relatively short time and is therefore still little known.

See also

literature

  • PH Weibye, NJ Berlin, KA Sjögren, JB Borck: New minerals from Norway. In: Annals of Physics and Chemistry. Volume 79, 1850, pp. 299–304 ( PDF 224.1 kB ; Katapleiit from p. 3)
  • GD Ilyushin, AA Voronkov, VV Ilyukhin, NN Nevskii, NV Belov: Crystal structure of natural monoclinic catapleiite, Na 2 ZrSi 3 O 9 · 2H 2 O. In: Soviet Physics Doklady Akademii Nauk SSSR . Volume 260, 1981, pp. 623-627 ( PDF 380.7 kB in Russian).

Web links

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

Individual evidence

  1. a b c d Friedrich Klockmann : Klockmann's textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp.  704 (as Katapleit) (first edition: 1891).
  2. 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.  471 .
  3. a b c d e 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.  596 .
  4. a b c d e Catapleiite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 ( PDF 76.1 kB ).
  5. a b c Petr Korbel, Milan Novák: Mineral Encyclopedia . Nebel Verlag GmbH, Eggolsheim 2002, ISBN 3-89555-076-0 , p. 470 (as Katapleit) ( Dörfler Natur ).
  6. a b c d e Mindat - Catapleiite
  7. perseus.tufts.edu - κατά
  8. perseus.tufts.edu - πλείων, πλέων, πλεῖον
  9. a b c PH Weibye, NJ Berlin, KA Sjogren, JB Borck: New minerals from Norway. In: Annals of Physics and Chemistry. Volume 79, 1850, pp. 299–304 ( PDF 224.1 kB ; Katapleiit from p. 3).
  10. Mineral Atlas: Catapleiite (Wiki)
  11. Mindat - Number of localities for Catapleiite
  12. Find location list for catapleiite at the Mineralienatlas and at Mindat
  13. ^ 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. 276 (as a katapleit) .