Senarmontit

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Senarmontit
Senarmontite-242475.jpg
Colorless octahedral senarmontite crystals from the type locality "Djebel Haminate Mine", Algeria ( overall size : 5.5 cm × 3.3 cm × 1.8 cm)
General and classification
other names

Senarmontite

chemical formula Sb 2 O 3
Mineral class
(and possibly department)
Oxides and hydroxides
System no. to Strunz
and to Dana
4.CB.50 ( 8th edition : IV / C.02)
03/04/09/02
Crystallographic Data
Crystal system cubic
Crystal class ; symbol cubic hexakisoctahedral; 4 / m  3  2 / m
Space group Fd 3 m (No. 227)Template: room group / 227
Lattice parameters a  = 11.15  Å
Formula units Z  = 16
Physical Properties
Mohs hardness 2 to 2.5
Density (g / cm 3 ) measured: 5.50; calculated: 5.584
Cleavage very clearly after {111}
Break ; Tenacity uneven to shell-like; brittle
colour colorless, off-white, orange to red by Metastibnit inclusions
Line color White
transparency transparent to translucent
shine Resin gloss to faint diamond gloss
Crystal optics
Refractive index n  = 2.087
Birefringence actually isotropic, but strong anomalous birefringence possible

Senarmontite (formerly Sénarmontite ) is a rather seldom occurring mineral from the mineral class of " oxides and hydroxides ". It crystallizes in the cubic crystal system with the chemical composition Sb 2 O 3 and is therefore chemically antimony (III) oxide .

Senarmontite usually develops well-formed octahedral crystals up to about three centimeters in size with a resin-like or slightly diamond-like sheen on the surfaces. Dodecahedral and other cubic combinations are also less common. In addition, it occurs in the form of crusty coatings or granular to massive mineral aggregates .

In its pure form, Senarmontite is colorless and transparent. By multiple light refraction due to lattice defects or polycrystalline but training can also appear gray and white by foreign admixtures in the form of Metastibnit - inclusions assume an orange to red color, the transparency decreases accordingly.

With a Mohs hardness of 2 to 2.5, senarmontite is one of the soft minerals that, like the reference mineral gypsum (2), can be scratched with a fingernail or like calcite (3) with a copper coin.

Etymology and history

Senarmontite was first discovered in the antimony mine "Djebel Hammimat" near Ain-el-Bebbouch in the Algerian province of Constantine and described in 1851 by Henri Hureau de Senarmont (1808-1862). However, he did not give the mineral a name, but only referred to it as "l'antimoine oxydé octaédrique" ( octahedral antimony oxide ). In the same year, Benjamin Silliman , Benjamin Silliman junior and James Dwight Dana published a summary of the newly discovered minerals ( Mineralogical Notices ) in the American Journal of Science and Arts, in which Dana suggested naming the mineral senarmontite after its first description.

Although Dana correctly spelled the mineral name according to that of the namesake, the name was given in many sources as Sénarmontit (e) . The correct spelling of the mineral name without the acute above the e was confirmed once again in Newsletter 28 of the IMA Commission on New Minerals, Nomenclature and Classification (CNMNC) published in 2015 .

classification

Already in the now outdated, but still in use 8th edition of the mineral classification according to Strunz , the senarmontite belonged to the mineral class of "oxides and hydroxides" and there to the department of "M 2 O 3 - and related compounds", where together with arsenolite , bismite , Russellit and Sillénit the "Arsenolite-Bismit-Gruppe" with the system no. IV / C.02 formed.

In the Lapis mineral directory according to Stefan Weiß, which, out of consideration for private collectors and institutional collections, is still based on this old form of Karl Hugo Strunz's system , the mineral was given the system and mineral number. IV / C.02-20 . In the "lapis Classification", this corresponds to the department "oxides with the molar ratio of metal: oxygen = 2: 3 (M 2 O 3 and related compounds)" where Senarmontit together with Arsenolith, bismite, Chrombismit , Dukeit , sillenite and Sphaerobismoite a forms an independent but unnamed group (as of 2018).

The 9th edition of the Strunz'schen mineral systematics , which has been valid since 2001 and updated by the IMA until 2009, also assigns the Senarmontite to the class of "oxides and hydroxides", but initially in the expanded section of "oxides with the molar ratio of metal: oxygen = 2: 3, 3: 5 and comparable “. This is further subdivided according to the relative size of the cations involved , so that the mineral can be found according to its composition in the sub-section “With medium-sized cations”, where the “arsenolite group” with system no. 4.CB.50 forms.

The systematics of minerals according to Dana also assigns the Senarmontite to the class of "oxides and hydroxides" and there in the department of "oxide minerals". Here it can also be found together with arsenolite in the unnamed group 04.03.09 within the subdivision of "Simple oxides with a cation charge of 3 + (A 2 O 3 )".

Chemism

The idealized (theoretical) composition of senarmontite (Sb 2 O 3 ) consists of antimony (Sb) and oxygen (O) in a molar ratio of 2: 3. This corresponds to a mass fraction (% by weight) of 83.54% Sb and 16.46 % O.

Crystal structure

Senarmontite crystallizes isotypically with arsenolite in the cubic crystal system in the space group Fd 3 m (space group no. 227) with the lattice parameter a  = 11.15  Å and 16 formula units per unit cell . Template: room group / 227

The crystal structure is similar to that of fluorite , but only 3/4 of the cation sites are occupied.

properties

In front of the soldering tube , senarmontite shows typical antimony reactions (light blue flame color , black condensation in the glow tube) and sublimates completely. It is soluble in hydrochloric acid .

As a cubic crystallizing mineral, senarmontite is normally optically isotropic with a refractive index of n = 2.087. However, strong anomalous birefringence is possible.

Modifications and varieties

The compound Sb 2 O 3 is dimorphic and, in addition to the cubic crystallizing senarmontite, also occurs as orthorhombic crystallizing valentinite .

Education and Locations

Gray Senarmontite from the type locality Djebel Haminate Mine, Algeria
(size: 4.8 cm × 3.4 cm × 2.2 cm)

Senarmontite forms secondarily through oxidation from antimony or various antimony minerals such as stibnite in hydrothermal antimony deposits . As Begleitminerale , you still can Cetineit , Kermesit , Mopungit , sulfur , Stibiconit and Valentinit occur.

As a rather rare mineral formation, senarmontite can sometimes be abundant at various sites, but overall it is not very common. A total of around 160 sites are known to date (as of 2014). In addition to its type locality , the “Djebel Hammimat” mine near Aïn-el-Bebbouch, the mineral was also found in the nearby “Djebel Senza” antimony mine in Algeria . "Djebel Hammimat" is also known for its exceptionally rich levels and crystals up to three centimeters in size.

In Germany, Senarmontite has so far been found in the Artenberg quarry near Steinach (Ortenaukreis) , near St. Ulrich in the Black Forest (Goldengründle, Gruenwald) and in an antimony mine near Sulzburg in Baden-Württemberg; in the “Silver Rose” mine near Brandholz- Goldkronach in Bavaria; in the Caspari colliery near Uentrop and the Wilder Mann mine near Müsen in North Rhine-Westphalia; in the “Carolina” mine at Moschellandsberg and the “Apollo” mine near Raubach in Rhineland-Palatinate; in the "Graf Jost-Christian-Zeche" near Wolfsberg (Sangerhausen) in Saxony-Anhalt; in the "Father Abraham" shaft near Lauta (Marienberg) , in the Freiberg mining area and in the Reimersgrün quarry near Limbach (Vogtland) in Saxony and in the Kuhberg quarry near Neumühle / Elster in Thuringia.

In Austria, the mineral could be found at Guggenbichl (Guginock) near Siflitz ( Kleblach-Lind municipality ), in the antimony deposit and slag heaps near Leßnig / Möllbrücke ( Lurnfeld municipality ) and in the Svata quarry near Terpetzen in Trixental in Carinthia.

The only known site in Switzerland so far is the “La Monda” mine near Aranno in the canton of Ticino.

Other locations include Australia, Chile, China, Finland, France, Greece, Greenland, Italy, Japan, Cambodia, Canada, Kyrgyzstan, Luxembourg, Malaysia, Mexico, New Caledonia, New Zealand, Norway, Portugal, Romania, Russia, Sweden, Serbia, Slovakia, Spain, South Africa, Tajikistan, the Czech Republic, Hungary, the United Kingdom (UK) and the United States of America (USA).

See also

literature

  • H. de Senarmont: Note on l'antimoine oxydé naturel de forme octaédrique . In: Annales de Chimie et de Physique . tape 31 , 1851, pp. 504–507 (French, rruff.info [PDF; 315 kB ; accessed on April 28, 2020]).
  • JD Dana : Mineralogical Notices. No. III. 1. New species. Octahedral oxide of antimony . In: American Journal of Science and Arts . tape 12 , 1851, pp. 205–222 ( [2] [PDF; 852 kB ; accessed on April 28, 2020]).
  • C. Svensson: Refinement of the crystal structure of cubic antimony trioxide, Sb 2 O 3 . In: Acta Crystallographica . B31, no. 8 , 1975, p. 2016–2018 , doi : 10.1107 / S0567740875006759 (English).

Web links

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

Individual evidence

  1. a b c d e f 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.  197 .
  2. a b c d Senarmontite . In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (Eds.): Handbook of Mineralogy, Mineralogical Society of America . 2001 (English, handbookofmineralogy.org [PDF; 69  kB ; accessed on April 28, 2020]).
  3. 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.  510 (first edition: 1891).
  4. a b Senarmontit. In: Mineralienatlas Lexikon. Stefan Schorn u. a., accessed on April 28, 2020 .
  5. 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.  415 .
  6. ^ Catalog of the German National Library - Henri de Senarmont (1808-1862). In: d-nb.info. German National Library , accessed on April 28, 2020 .
  7. ^ IMA Commission on New Minerals, Nomenclature and Classification (CNMNC). Newsletter 28 . In: Mineralogical Magazine . tape  79 , no. 7 , December 2015, p. 1859–1864 (English, [1] [PDF; 69 kB ; accessed on April 28, 2020]).
  8. Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties. Status 03/2018 . 7th, completely revised and supplemented edition. Weise, Munich 2018, ISBN 978-3-921656-83-9 .
  9. Ernest H. Nickel, Monte C. Nichols: IMA / CNMNC List of Minerals 2009. (PDF; 1.82 MB) In: cnmnc.main.jp. IMA / CNMNC, January 2009, accessed April 28, 2020 .
  10. ^ Helmut Schrätze , Karl-Ludwig Weiner : Mineralogie. A textbook on a systematic basis . de Gruyter, Berlin; New York 1981, ISBN 3-11-006823-0 , pp.  388 .
  11. Localities for Senarmontite. In: mindat.org. Hudson Institute of Mineralogy, accessed April 28, 2020 .
  12. Petr Korbel, Milan Novák: Mineral Encyclopedia (=  Dörfler Natur ). Edition Dörfler im Nebel-Verlag, Eggolsheim 2002, ISBN 978-3-89555-076-8 , p. 81 .
  13. Find location list for Senarmontite at the Mineralienatlas and at Mindat , accessed on April 28, 2020.