Inesit

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Inesit
Inesite-k272a.jpg
Thin-sheet inesite from the Wessels Mine, Hotazel, Kalahari Manganese Field, North Cape, South Africa
General and classification
chemical formula Ca 2 Mn 7 [(OH) 2 | Si 10 O 28 ] • 5H 2 O
Mineral class
(and possibly department) 		Silicates and germanates - chain and band silicates
System no. to Strunz
and to Dana 		9.DL.05 ( 8th edition : VIII / F.27)
66.03.03.01
Crystallographic Data
Crystal system triclinic
Crystal class ; symbol triclinic pinacoidal; 1
Space group P 1 (No. 2)Template: room group / 2
Lattice parameters a  = 8.89  Å ; b  = 9.25 Å; c  = 11.98 Å,
α  = 88.1 °; β  = 132.1 °; γ  = 96.6 °
Formula units Z  = 1
Physical Properties
Mohs hardness 5.5 to 6
Density (g / cm 3 ) measured: 3.03 to 3.04; calculated: 3.03
Cleavage perfect after {010}, good after {100}
Break ; Tenacity uneven; brittle
colour pink to wine red, orange or brown in various shades
Line color White
transparency transparent to translucent
shine Glass gloss, silk gloss
Crystal optics
Refractive indices n α  = 1.609
n β  = 1.636
n γ  = 1.644
Birefringence δ = 0.035
Optical character biaxial negative
Axis angle 2V = measured: 60 °; calculated: 56 °

The mineral Inesit is a chain silicate from the mineral class of " silicates and germanates " with the chemical composition Ca 2 Mn 7 [(OH) 2 | Si 10 O 28 ] · 5H 2 O and is therefore chemically a water-containing calcium - manganese- silicate with additional hydroxide ions .

Inesit crystallizes in the triclinic crystal system and develops mostly transparent to translucent crystals up to about 7 cm in length with a tabular, needle-like or fibrous habit of pink, orange or brown in various shades that appear flesh-colored (see etymology ). The stroke color of Inesit however, is always white. The surfaces of the crystals show a glassy sheen , which, however, changes into a more pearly sheen in the acicular to fibrous, radial and massive aggregate shape that is also common .

Etymology and history

Inesit was first discovered in the "Grube Hilfe Gottes" near Oberscheld (Dillenburg) in Hesse and was described in 1887 by Adolf Schneider , who derived the mineral due to its characteristic pink color and its often needle-like to fibrous habit from the Greek word ἶνες [ínes] for " Tendons, muscles ”.

Type material of the mineral is in the Mineralogical Museum of the Philipps University of Marburg under the catalog no. MMM K35 / 14 kept.

classification

Already in the outdated but still in use 8th edition of the mineral classification by Strunz of Inesit belonged to the mineral class of "silicates and Germanates" and then to the Department of "chain silicates and band silicates (inosilicates)" where he collaborated with Babingtonit , 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 force since 2001 and is used by the International Mineralogical Association (IMA), also classifies Inesit in the category of "chain and band silicates (inosilicates)". This is, however, further subdivided according to the structure of the chains, so that the mineral, according to its crystal structure, can be found in the sub-section "Chain and band silicates with 5-periodic double chains, Si 10 O 28 ", where it is the only member of the unnamed group 9 .DL.05 forms.

The systematics of minerals according to Dana also assigns Inesit to the class of "silicates and germanates", but there in the department of "chain silicates: double unbranched chains, W = 2". Here he is the only member of the group "P = 5" with the system no. 66.03.03 to be found in the subsection “ Chain silicates: Double unbranched chains, W = 2 with chains P> 2 ”.

Crystal structure

Inesite crystallizes triclinically in the space group P 1 (space group no. 2) with the lattice parameters a  = 8.89  Å ; b  = 9.25 Å; c  = 11.98 Å; α  = 88.1 °; β  = 132.1 ° and γ  = 96.6 ° and one formula unit per unit cell . Template: room group / 2

At a temperature of about 800 ° C under Inesit converts loss of its water of crystallisation its crystal structure in which the Rhodonits order.

Education and Locations

Inesite and xonotlite (white) on Marienglas (variety of gypsum) from the Wessels Mine, Hotazel, Kalahari Manganese Field, North Cape, South Africa

Inesite forms in a late stage of crystallizing hydrothermal solutions in manganese-containing deposits, mostly in paragenesis with rhodochrosite , cementite and hausmannite such as in the "Hale Creek Mine" on Mad River Ridge in Trinity County (California, USA) or with datolite , pectolite , Apophyllit , Ruizit , Orientit and quartz , such as in the "Wessels mine" at Hotazel in the manga field of the Kalahari in Africa.

As a rare mineral formation, Inesit could only be detected at a few sites, although around 60 sites are known to date (as of 2017).

In Germany, apart from the type locality "Grube Hilfe Gottes" and the nearby Nanzenbach in Dillenburg in Hesse, no other sites are known.

Other locations include Broken Hill in Australia, Daye ("Fengjiashan Mine") in China, Java and Sumatra in Indonesia, Liguria and Lombardy in Italy, Hokkaidō , Honshū and Shikoku in Japan, the San Cayetano Mine in the Mexican state of Durango , Waihi ("Martha Mine") in New Zealand, several regions in Sweden , Banská Štiavnica in Slovakia, Gualba in Spain, several positions in the Kalahari manganese field in South Africa, Gyöngyösoroszi in the Hungarian Mátra Mountains and several regions in the United States (USA) .

See also

literature

  • A. Schneider: Negotiations of the company. Minutes of the November meeting. About new manganese ores from Dillenburg . In: Journal of the German Geological Society . tape 39 , 1887, p. 829-834 ( rruff.info [PDF; 406 kB ; accessed on June 10, 2017]).
  • Che'ng Wan, Subrata Ghose: Inesite, a hydrated calcium manganese silicate with five-tetrahedral-repeat double chains . In: American Mineralogist . tape 63 , 1978, pp. 563-571 ( rruff.info [PDF; 1.1 MB ; accessed on June 10, 2017]).
  • Petr Korbel, Milan Novák: Mineral Encyclopedia (=  Villager Nature ). Nebel Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 246 .

Web links

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

Individual evidence

  1. ↑ a b c d e 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.  649 .
  2. ↑ Webmineral - Inesite (English)
  3. ↑ a b c Inesite . 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 ]).
  4. ↑ a b c d e Mindat - Inesite (English)
  5. ↑ Janet H. Clifford: Connoisseur's Choice: Inesite, Wessels Mine, Northwest of Kuruman, Kalahari Manganese District, Cape Province, South Africa . In: Rocks & Minerals . tape 86 , no. 3 , May 23, 2011, p. 250–260 , doi : 10.1080 / 00357529.2011.568351 ( limited preview on tandfonline.com [accessed June 10, 2017]).
  6. ^ Albert Huntington Chester : A dictionary of the names of minerals including their history and etymology . 1st edition. John Wiley & Sons, New York 1896, p.  134 ( archive.org [accessed June 10, 2017]).
  7. ↑ Type mineral catalog Germany, Mineralogical Museum of the University of Hamburg. Inesit
  8. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke, Stuttgart 1978, ISBN 3-432-82986-8 , pp.  735, 842 (first edition: 1891).
  9. ↑ Mindat - Number of locations for Inesit
  10. ↑ Find location list for Inesit at the Mineralienatlas and at Mindat