Alabandin

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Alabandin
Alabandite - Uchucchacua Mine, Oyon, Lima, Peru.jpg
Alabandite crystal specimen from the Uchucchacua Mine, Oyon Province , Peru Overall
size of the specimen approx. 7.5 × 3.8 cm; largest single crystal approx. 2.5 cm
General and classification
chemical formula α-MnS
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.CD.10 ( 8th edition : II / C.15)
08/02/01/04
Crystallographic Data
Crystal system cubic
Crystal class ; symbol hexakisoctahedral 4 / m 3 2 / m
Room group (no.) Fm 3 m (No. 225)
Lattice parameters a  = 5.22  Å
Formula units Z  = 4
Frequent crystal faces (111), (100), (110), (211)
Twinning after (111)
Physical Properties
Mohs hardness 3.5 to 4
Density (g / cm 3 ) 3.95 to 4.04
Cleavage completely after (100)
Break ; Tenacity uneven
colour black, steel gray, brownish black
Line color green
transparency opaque, translucent in very thin layers
shine Metallic luster
Crystal optics
Refractive index n  = 2.70
Birefringence none, as isotropic

Alabandin , also under the mining names Manga panel , Manga gloss , Braunstein panel and Braunstein gravel , discloses a mineral from the mineral class of " sulfides and sulfosalts " which can be abundant in various localities in part, but altogether not widespread.

Alabandin crystallizes in the cubic crystal system with the chemical composition α-MnS or MnS for short, so from a chemical point of view it is a manganese (II) sulfide that occurs naturally in the form of cubic or octahedral crystals , but also granular to massive aggregates in black, steel-gray or brownish black color is found.

Etymology and history

Alabandin was named after its alleged first place of discovery, Alabanda, in Turkey. In fact, in contrast to the garnet mineral almandine , which is also named after this place, the mineral has never been detected in Turkey.

Alabandin was first described in 1784 by Franz Joseph Müller von Reichenstein . The Romanian town of Sacarîmb in the Hunedoara district is considered the type locality today .

classification

In the meanwhile outdated, but still in use 8th edition of the mineral classification according to Strunz , the alabandin belonged to the mineral class of "sulfides and sulfosalts" and there to the department of "metal: sulfur, selenium, tellurium = 1: 1", where it belongs together with Altait , Clausthalit , Crerarit , Galenit , Keilit , Niningerit and Oldhamit formed the unnamed group II / C.15 .

The 9th edition of Strunz's mineral systematics , valid since 2001 and used by the IMA, also assigns the alabandin to the class of "sulfides and sulfosalts", more precisely the sulfides, selenides, tellurides, arsenides, antimonides, bismuthides, sulfarsenites, sulfantimonites and sulfbismuthites , and there in the section of "Metal sulfides, M: S = 1: 1 (and similar)". However, this section is now more precisely subdivided according to the type of cations involved , so that the mineral can be found according to its composition in the subdivision "with tin (Sn), lead (Pb), mercury (Hg) etc.", where it can be found together with Altaite, Clausthalite, Crerarite, Cuboargyrite , Galenite, Keilit, Niningerite, Oldhamite and Schapbachite form the unnamed group 2.CD.10 .

The systematics of minerals according to Dana also assigns the alabandin to the class of "sulphides and sulphosalts", but there in the category of "sulphide minerals". Here he is a member of the " Galena Group (isometric: Fm3m)" with the system no. 02.08.01 and the other members Clausthalit, Altait, Oldhamit, Niningerit, Borovskit , Crerarit and Keilit within the subdivision of “ Sulphides - including selenides and tellurides - with the composition A m B n X p , with (m + n): p = 1: 1 ".

Crystal structure

Alabandin crystallizes in the cubic crystal system with the space group Fm 3 m (space group no. 225) with the lattice parameter a  = 5.22  Å and 4 formula units per unit cell .

properties

The mineral is usually opaque and shows a metallic to semi-metallic luster on the crystal surfaces only when fresh . After a while, it turns brownish-black and becomes matt. Alabandin leaves a green line on the whiteboard .

Alabandin is before the blowtorch difficult fusible.

Modifications and varieties

The compound MnS (manganese (II) sulfide) is dimorphic , which means that it occurs in nature in addition to the cubic modification of alabandin as hexagonally crystallizing rambergite .

Education and Locations

Alabandin with rhodochrosite and quartz from the Uchucchacua Mine, Oyón Province , Peru (size: 84 mm × 58 mm × 45 mm)

Alabandin forms hydrothermally in vein deposits (ore veins), whereby it is often found in paragenesis with galena , pyrite , sphalerite , rhodochrosite , calcite and others.

In total, alabandin has so far (as of 2011) been detected at around 230 sites. In addition to its type locality Sacarîmb, where the largest crystals to date were found with a diameter of up to two centimeters, the mineral occurred in Romania at Brad in the Hunedoara district and at Roșia Montană in the Alba district.

In Germany, alabandin was found in the Segen Gottes mine near Gersdorf in the Striegistal municipality (about 20 km northwest of Freiberg) and in the remains of the old mining area near Berggießhübel . Another place where it was found, the dump near Ronneburg in Thuringia, no longer exists.

In Switzerland, alabandin has so far only been found at the water tunnel of the Amsteg power plant in the municipality of Silenen UR , which belongs to the canton of Uri .

Other locations are the Antarctic , Argentina , Armenia , Australia , Bolivia , Brazil , Bulgaria , China , Finland , France , Ghana , Greece , Greenland , India , Italy , Japan , Yemen , Canada , Kyrgyzstan, Mexico , Namibia , New Zealand , Norway , Peru , Poland , Russia , Sweden , Slovakia , South Africa , South Korea , Taiwan , Tanzania , Czech Republic , Uzbekistan , the United Kingdom (Great Britain) and the United States of America (USA).

See also

literature

Web links

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

Individual evidence

  1. ↑ a b c d 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. 90 .
  2. ↑ a b Alabandite at mindat.org (engl.)
  3. ↑ Mineralienatlas: locality list for Alabandin
  4. ↑ Mindat - Localities for Alabandin
  5. ↑ www.mineral.hermuz.hu - A Kárpát-övezetben felfedezett ásványok
  6. ↑ Mindat - Sacarîmb (Sãcãrâmb; Szekerembe; Nagyág), Hunedoara Co., Romania (description of the place of discovery and list of mineral finds)
  7. ↑ Mineral Atlas: Grube Segen Gottes (description of the location and mineral list)
  8. ↑ Mineral Atlas: The old mining area of ​​Berggießhübel in the Eastern Ore Mountains (description of the location and mineral list)
  9. ↑ Mineralienatlas: Ronneburg waste dump (description of the location and mineral list)