Allendeit

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Allendeit
General and classification
other names

IMA 2007-027

chemical formula Sc 4 Zr 3 O 12
Mineral class
(and possibly department) 		Oxides and hydroxides
System no. to Strunz
and to Dana 		4.C
11/07/11/02
Crystallographic Data
Crystal system trigonal
Crystal class ; symbol trigonal-rhombohedral; 3
Space group R 3 (No. 148)Template: room group / 148
Lattice parameters a  = 9.396  Å ; c  = 8.720 Å
Formula units Z  = 3
Physical Properties
Mohs hardness not defined
Density (g / cm 3 ) calculated: 4.84
Cleavage not defined
colour not defined
Line color not defined
transparency not defined
shine not defined

Allendeit is a very rarely occurring mineral from the mineral class of "oxides and hydroxides". It crystallizes in the trigonal crystal system with the chemical composition Sc 4 Zr 3 O 12 and is therefore a scandium - Zirconium - oxide .

Allendeit has so far only been discovered in the form of microcrystalline inclusions of around 10 to 25 μm in size in meteorites . For this reason, no information can currently be given regarding color, line color , Mohs hardness , transparency and gloss .

Etymology and history

Allendeite was first discovered together with hexamolybdenum 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 type locality and submitted it to the International Mineralogical Association (IMA) for examination in 2007 (internal register no. 2007-027). 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".

classification

Since Allendeit 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and recognized as an independent mineral, it is not listed in the Strunz mineral system (8th edition), which has been outdated since 2001 .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 valid since 2001 and is used by the IMA, assigns the Allendeit to the class of "oxides and hydroxides" and there into the department of "oxides with the molar ratio of metal: oxygen = 2: 3, 3: where he 5 and comparable "as the only member of the unnamed group 4.C forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns Allendeit to the class of "oxides and hydroxides" and there in the department of "multiple oxides". Here it can be found together with Mongshanit in the unnamed group 11/07/11 within the sub-section “Multiple oxides as titanium oxides with [4] and [6] substitutions”.

Crystal structure

Allendeit crystallizes trigonally in the space group R 3 (space group no. 148) with the lattice parameters a  = 9.396  Å and c  = 8.720 Å as well as 3 formula units per unit cell . Template: room group / 148

Education and Locations

In addition to its type locality , the Mexican Allende meteorite , the mineral has so far (as of 2014) only been found in a meteorite that fell in 1983 near Ningqiang in the Chinese province of Shaanxi.

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 .

Web links

Individual evidence

  1. ↑ a b c d e f 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 .
  2. ↑ Mindat - description of the location and mineral list for Ningqiang meteorite (Ningqiang carbonaceous chondrite), Ningqiang Co., Hanzhong Prefecture, Shaanxi Province, China
  3. ↑ Find location list for Allendeit at the Mineralienatlas and at Mindat