Mutnovskit

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Mutnovskit
General and classification
other names

IMA 2004-032

chemical formula Pb 2 AsS 3 (I, Cl, Br)
Mineral class
(and possibly department) 		Sulfides and sulfosalts
System no. to Strunz
and to Dana 		2.GC.50 ( 8th edition : II / E.27)
02.15.07.01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol orthorhombic-dipyramidal; 2 / m  2 / m  2 / m
Space group Pnma (No. 62)Template: room group / 62
Lattice parameters a  = 11.543 (1)  Å ; b  = 6.6764 (7) Å; c  = 9.359 (1) Å
Formula units Z  = 4
Physical Properties
Mohs hardness 2
Density (g / cm 3 ) calculated: 6.177
Cleavage is missing
Break ; Tenacity is missing; soft and fragile
colour ruby red, dark red to blue
Line color cherry red to orange
transparency translucent, translucent in thin fragments
shine Resin gloss, faint metallic gloss

Mutnovskite is a very rarely occurring mineral from the mineral class of "sulfides and sulfosalts" with the chemical composition Pb 2 AsS 3 (I, Cl, Br). Mutnovskit thus consists of lead , arsenic and sulfur in a molar ratio of 2: 1: 3 and also contains iodine , chlorine and bromine in variable proportions, which can represent each other in the formula , but are always in the same proportion to the other components of the mineral . Structurally, Mutnovskite belongs to the sulfo salts .

Mutnovskite crystallizes in the orthorhombic crystal system and has so far only been found in the form of microscopic, short-prismatic crystals of up to 100  μm from ruby ​​red to dark red or blue in color. In the incident light, however, Mutnovskit shows a silvery-lead-gray color with an iridescent coating.

Mutnovskit is the first naturally occurring sulfo salt containing iodine. Both the chemical composition and the X-ray powder data show that the mineral has no analogues among minerals or synthetic compounds.

Etymology and history

Was first discovered Mutnovskit 2004 a high-temperature fumaroles on the volcano Mutnovsky (English: Mutnovsky ) in the southern part of the Russian peninsula of Kamchatka in the Far Eastern Federal District . The mineral was scientifically described by Michael Zelenski, Tonči Balić-Žunić, Luca Bindi, Anna Garavelli, Emil Makovicky, Daniela Pinto and Filippo Vurro, who named it after its type locality . The full mineral description and the chosen name were submitted to the International Mineralogical Association (IMA) for review (IMA accession number : 2004-032 ) and approved in the same year. The publication of the new discovery followed in 2006 in the science magazine American Mineralogist .

The type material of the mineral is kept in the mineralogical collection of the CL Garavelli Museum of the University of Bari under the catalog number 7 / nm (V28).

classification

Since Mutnovskit was only recognized as an independent mineral by the International Mineralogical Association (IMA) in 2004 , it is not listed in the 8th edition of the Strunz mineral systematics published in 1982. Only in the "Lapis mineral directory", which is still based on the classical system of Karl Hugo Strunz out of consideration for private collectors and institutional collections , the mineral received the system no. II / E.27 -30 .

The 9th edition of Strunz's mineral systematics, which has been in effect since 2001 and is used by the IMA, assigns the Mutnovskite to the class of “sulfides and sulfosalts” and there to the section of “sulfoarsenides, sulfoantimonides, sulfobismutides”. This is further subdivided according to the structure of the sulfarsenides, -antimonides and -bismutides, so that the mineral can be found according to its composition in the sub-section "Poly-sulfarsenides", where it is the only member of the unnamed group 2.GC.50 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Mutnovskite to the class of "sulides and sulphosalts", although there it belongs to the category of "sulphide minerals". Here he is to be found as the only member of the unnamed group 02.15.07 within the sub-section "Sulphides - including selenides and tellurides - chlorides".

Crystal structure

Mutnovskite crystallizes orthorhombically in the space group Pnma (space group no. 62) with the lattice parameters a  = 11.543 (1)  Å ; b  = 6.6764 (7) Å and c  = 9.359 (1) Å as well as 4 formula units per unit cell . Template: room group / 62

At a temperature of 110K, Mutnovskit changes reversibly into a non- centrosymmetric orthorhombic structure type with the space group Pnm 2 1 (No. 31, position 2) and the lattice parameters a  = 11.5394 (9) Å, b  = 6.6732 (5) Å and c  = 9.3454 (7) Å and 2 formula units per unit cell µm. Template: room group / 31.2

Education and Locations

Mutnovskite forms as a resublimation product on volcanic fumaroles at a temperature of around 250 ° C. As Begleitminerale occurred among other Kudriavit cadmium, Cannizzarit and other Pb-Bi-As-sulfosalts and anhydrite , cristobalite and pyrite on.

Apart from its type locality, the fumarole located about 13 km southeast of the Mutnovsky crater ( 52 ° 21 ′ 0 ″  N , 158 ° 16 ′ 12 ″  E ), no other sites for Mutnovskite are known so far (as of 2017).

See also

literature

  • Michael Zelenski, Tonči Balić-Žunić, Luca Bindi, Anna Garavelli, Emil Makovicky, Daniela Pinto, Filippo Vurro: First occurrence of iodine in natural sulfosalts: The case of mutnovskite, Pb 2 AsS 3 (I, Cl, Br), a new mineral from the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation . In: American Mineralogist . tape 91 , 2006, p. 21–28 ( rruff.info [PDF; 410 kB ; accessed on November 27, 2017]).
  • Luca Bindi, Anna Garavelli, Daniela Pinto, Giovanni Pratesia, Filippo Vurro: Ordered distribution of I and Cl in the low-temperature crystal structure of mutnovskite, Pb4As2S6ICl: An X-ray single-crystal study . In: Journal of Solid State Chemistry . tape 181 , no. 2 , 2008, p. 306-312 , doi : 10.1016 / j.jssc.2007.11.032 .

Web links

Individual evidence

  1. ↑ a b IMA / CNMNC List of Mineral Names; September 2017 (PDF 1.7 MB)
  2. ↑ a b 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 .
  3. ↑ Webmineral - Mutnovskite (English)
  4. ↑ a b c d e f g h i Michael Zelenski, Tonči Balić-Žunić, Luca Bindi, Anna Garavelli, Emil Makovicky, Daniela Pinto, Filippo Vurro: First occurrence of iodine in natural sulfosalts: The case of mutnovskite, Pb 2 AsS 3 (I, Cl, Br), a new mineral from the Mutnovsky volcano, Kamchatka Peninsula, Russian Federation . In: American Mineralogist . tape 91 , 2006, p. 21–28 ( rruff.info [PDF; 410 kB ; accessed on November 27, 2017]).
  5. ↑ Luca Bindi, Anna Garavelli, Daniela Pinto, Giovanni Pratesia, Filippo Vurro: Ordered distribution of I and Cl in the low-temperature crystal structure of mutnovskite, Pb4As2S6ICl: An X-ray single-crystal study . In: Journal of Solid State Chemistry . tape 181 , no. 2 , 2008, p. 306-312 , doi : 10.1016 / j.jssc.2007.11.032 .
  6. ↑ Find location list for Mutnovskite at the Mineralienatlas and at Mindat