Namansilite

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Namansilite
Namansilite-486505.jpg
Purple namansilite inclusions in granular quartz from the Woods Mine near Tamworth , New South Wales, Australia (sample diameter 100 mm)
General and classification
other names

IMA 1989-026

chemical formula NaMn 3+ [Si 2 O 6 ]
Mineral class
(and possibly department) 		Silicates and germanates - chain and band silicates (inosilicates)
System no. to Strunz
and to Dana 		9.DA.25 ( 8th edition : VIII / F.01)
65.01.03c.03
Crystallographic Data
Crystal system monoclinic
Crystal class ; symbol monoclinic prismatic; 2 / m
Space group C 2 / c (No. 15)Template: room group / 15
Lattice parameters a  = 9.50  Å ; b  = 8.61 Å; c  = 5.36 Å
β  = 105.0 °
Formula units Z  = 4
Twinning polysynthetic according to {100}
Physical Properties
Mohs hardness 6 to 7
Density (g / cm 3 ) measured: 3.51; calculated: [3.61]
Cleavage completely after {110}
Break ; Tenacity brittle
colour red-violet
Line color brownish purple
transparency transparent
shine Diamond luster; Glass to pearlescent
Crystal optics
Refractive indices n α  = 1.746
n β  = 1.769
n γ  = 1.837
Birefringence δ = 0.091
Optical character biaxial negative
Axis angle 2V = 15 ° to 20 ° (measured), 64 ° (calculated)

Namansilite is a very rarely occurring mineral from the mineral class of "silicates and germanates" with the chemical composition NaMn 3+ [Si 2 O 6 ] and is therefore chemically a sodium - manganese - silicate from the pyroxene group . Structurally, namansilite belongs to the chain silicates .

Namansilite crystallizes in the monoclinic crystal system and develops prismatic crystals up to about two millimeters in length in granular mineral aggregates . Namansilite can also be found in the form of inclusions in other minerals such as quartz . The mineral is transparent and has a red-violet color with a brownish-violet streak color .

Etymology and history

Namansilite was first discovered in the Ir-Nimi-Manganese deposit on the Taikan Ridge in the Khabarovsk region in the Russian Federation Far East and described in 1992 by VV Kalinin, IM Marsii, YP Dikov, NV Troneva and NV Trubkin who named the mineral after his composition ( Na trium, Man gan, Sil ICIUM) and the usual for minerals attachment, it notified '.

Type material of the mineral is kept in the Fersman Museum in Moscow .

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the namansilite belonged to the mineral class of "silicates and germanates" and there to the department of "chain silicates and band silicates (inosilicates)", where it belonged together with aegirine , augite , diopside , Esseneit , Hedenbergit , Jadeit , Jervisit , Johannsenite , kanoite , clino-enstatite , Klinoferrosilit , Kosmochlor , Natalyit , omphacite , Petedunnit , pigeonite and spodumene the "subset of clinopyroxene" with the system number. VIII / F.01 .

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 namansilite in the category of "chain and band silicates (inosilicates)". However, this is further subdivided according to the structure of the silicate chains, so that the mineral is classified in the sub-section “Chain and band silicates with 2-periodic single chains Si 2 O 6 ; Pyroxene family "can be found, where only together with aegirine, jadeite, jervisite, cosmochlor and natalyite, the" Na-clinopyroxene "or" jadeite group "with the system no. 9.DA.25 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Namansilite to the class of "silicates and Germanates" and there in the department of "chain silicate minerals". Here it is in the " C2 / c Klinopyroxene (Na-Klinopyroxene) " with the system no. 65.01.03c within the sub-section “Chain Silicates: Simple unbranched chains, W = 1 with chains P = 2”.

Crystal structure

Namansilite crystallizes monoclinically in the space group C 2 / c (space group no. 15) with the lattice parameters a  = 9.50  Å ; b  = 8.61 Å; c  = 5.36 Å and β = 105.0 ° and 4 formula units per unit cell . Template: room group / 15

Education and Locations

Namansilite forms in low-grade metamorphosed and strongly oxidized and manganese and sodium-rich sediments.

As a very rare mineral formation, namansilite is only known from a few samples at fewer than 10 sites (as of 2016). Its type locality , the Ir-Nimi-Manganese deposit, is the only site in Russia to date.

The only known site in Germany is the "Caspar" quarry on the Bellerberg volcano near Ettringen in Rhineland-Palatinate.

Other well-known sites are the Woods Mine near Tamworth and the Hoskins Mine near Grenfell in Australia, the Cerchiara Mine near Borghetto di Vara in the Italian region of Liguria, the Shimoharai Mine near Saiki on the Japanese island of Kyushu and the Assitza Mine near Iacobeni (Suceava ) in the Romanian district of Suceava .

See also

literature

  • VV Kalinin, IM Marsii, YP Dikov, NV Troneva, NV Trubkin: Namansilite NaMn 3+ Si 2 O 6 : a new silicate . In: Zapiski Vserossijskogo Mineralogicheskogo Obshchestva . tape 121 , no. 1 , 1992, p. 89–94 ( rruff.info [PDF; 559 kB ]).
  • Haruo Ohashi, Toshikazu Osawa, Katsuhiro Tsukimura: Refinement of structure of manganese sodium dimetasilicate . In: Acta Crystallographica . C43, 1987, pp. 605-607 , doi : 10.1107 / S0108270187094836 .
  • John Leslie Jambor , David A. Vanko: New mineral names. Namansilite . In: American Mineralogist . tape 78 , 1993, p. 1314–1319 ( rruff.info [PDF; 1.1 MB ]).

Web links

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

Individual evidence

  1. ↑ a b c d 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.  621 .
  2. ↑ Webmineral - Namansilite
  3. ↑ a b c d Namansilite , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 75 kB )
  4. ↑ 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 .
  5. ↑ a b c d e Mindat - Namansilite
  6. ↑ Mindat - Number of localities for Namansilite
  7. ↑ Find location list for Namansilit in the Mineralienatlas and Mindat