Hexamolybdenum

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Hexamolybdenum
General and classification
other names
  • Hexamolybdenum
  • IMA 2007-029
chemical formula
  • (Mo, Ru, Fe, Ir, Os)
  • (Mo, Ru, Ir)
Mineral class
(and possibly department) 		elements
System no. to Strunz
and to Dana 		1.AB.05 ( 8th edition : I / A.13)
02/01/02/05
Crystallographic Data
Crystal system hexagonal
Crystal class ; symbol dihexagonal-dipyramidal; 6 / m  2 / m  2 / m
Space group P 6 3 / mmc (No. 194)Template: room group / 194
Lattice parameters a  = 2.7506  Å ; c  = 4.4318 Å
Formula units Z  = 2
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) calculated: 11.90
Cleavage is missing
colour Gray
Line color not defined
transparency opaque (opaque)
shine Metallic luster

Hexamolybdenum is a very rarely occurring mineral from the mineral class of "elements (including natural alloys, intermetallic compounds, carbides, nitrides, phosphides and silicides)" with the chemical composition (Mo, Ru, Fe, Ir, Os) and is therefore seen chemically a natural alloy of molybdenum , ruthenium , iron , iridium and osmium , with the molybdenum content predominating.

Hexamolybdenum crystallizes in the hexagonal crystal system , but has so far only been found in the form of microcrystalline, idiomorphic grains up to about 1.2 μm in size or as inclusions in other minerals.

Etymology and history

Hexamolybdenum was first discovered together with Allendeit in 2007 in the Allende meteorite , which fell over Mexico in 1969 and partly hit Pueblito de Allende in the state of Chihuahua . The mineral was described by Chi Ma, John R. Beckett and George R. Rossman, who named it after its hexagonal symmetry and the main component molybdenum. The mineral description and chosen name have been submitted to the International Mineralogical Association (IMA) for review (internal register no. 2007-029). This recognized the mineral as independent in the same year. The publication of the new discovery followed in 2009 in the 40th "Lunar and Planetary Science Conference" and in 2014 in the science magazine American Mineralogist .

Type material , i.e. mineral samples from the type locality, are stored in the National Museum of Natural History in Washington, DC (USA) under catalog no. USNM 3509HC12 and 7590 retained .

classification

Since hexamolybdenum was only discovered in 2007 and recognized as an independent mineral, it is not listed in the Strunz mineral system (8th edition), which has been outdated since 2001 .

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 hexamolybdenum in the “Metals and Intermetallic Compounds” section. However, this is further subdivided according to the predominant metals in the compound, which have been divided into metal families according to their related properties. Hexamolybdenum can be found here according to its composition in the sub-section “zinc-brass family”, where together with cadmium , titanium and zinc it forms the “zinc group” with system no. 1.AB.05 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns hexamolybdenum to the class and there in the department of the same name of "elements". Here it is together with osmium, ruthenium, rutheniridosmin, hexaferrum and garutiit in the " osmium group (space group P63 / mmc) " with the system no. 02/01/02 within the sub-section “Elements: Platinum Group Metals and Alloys”.

Crystal structure

Hexamolybdenum crystallizes hexagonally in the space group P 6 3 / mmc (space group no. 194) with the lattice parameters a  = 2.7506  Å and c  = 4.4318 Å and two formula units per unit cell . Template: room group / 194

Education and Locations

In its type locality, the Allende meteorite, the Hexamolybdän grains formed in an egg-shaped, extremely fire-proof enclosure and joined there with perovskite , various Os Ir-Mo-W alloys and Sc-stabilized Tazheranit associated to.

The only known meteorite sites for hexamolybdenum so far (as of 2017) are the meteorite Murchison , which fell in the Australian state of Victoria in 1969, and the carbonaceous chondrite of class CV3 NWA 1934 found in Northwest Africa in 2003 .

In addition, we still found the mineral in a heavy mineral - soap on the Danube near Straubing Germany in Bavaria.

See also

literature

  • Chi Ma, John R. Beckett, George R. Rossman: Allendeite (Sc 4 Zr 3 O 12 ) and hexamolybdenum (Mo, Ru, Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite . In: 40th Lunar and Planetary Science Conference . 2009 ( usra.edu [PDF; 992 kB ; accessed on January 4, 2018]).
  • Chi Ma, John R. Beckett, George R. Rossman: Allendeite (Sc 4 Zr 3 O 12 ) and hexamolybdenum (Mo, Ru, Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite . In: American Mineralogist . tape 99 , no. 4 , 2014, p. 654–666 , doi : 10.2138 / am.2014.4667 (accessed via De Gruyter Online).

Web links

Individual evidence

  1. ↑ a b c d e Stefan Weiss: The great 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 .
  2. ↑ a b c IMA / CNMNC List of Mineral Names; September 2017 (PDF 1.67 MB)
  3. ↑ a b c d e Chi Ma, John R. Beckett, George R. Rossman: Allendeite (Sc 4 Zr 3 O 12 ) and hexamolybdenum (Mo, Ru, Fe), two new minerals from an ultrarefractory inclusion from the Allende meteorite . In: American Mineralogist . tape 99 , no. 4 , 2014, p. 654–666 , doi : 10.2138 / am.2014.4667 (accessed via De Gruyter Online).
  4. ↑ Webmineral - Hexamolybdenum
  5. ↑ a b c Hexamolybdenum . 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; 85  kB ; accessed on January 2, 2018]).
  6. ↑ a b List of locations for hexamolybdenum in the Mineralienatlas and Mindat