Cupalite

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Cupalite
General and classification
other names

IMA 1983-084

chemical formula
  • CuAl
  • (Cu, Zn) Al
Mineral class
(and possibly department) 		Elements - metals and intermetallic alloys
System no. to Strunz
and to Dana 		1.AA.20 ( 8th edition : I / A.03)
01.01.15.01
Crystallographic Data
Crystal system orthorhombic
Crystal class ; symbol Please complete!
Lattice parameters a  = 6.95 (1)  Å ; b  = 4.16 (1) Å; c  = 10.04 (1) Å
Formula units Z  = 10
Physical Properties
Mohs hardness 4 to 4.5 (VHN 20 and 50 = 272 to 318)
Density (g / cm 3 ) calculated: 5.12
Cleavage Please complete!
colour grey yellow
Line color Please complete!
transparency opaque
shine Metallic luster

Cupalite is a very rarely occurring mineral from the mineral class of the "elements (including natural alloys or intermetallic compounds, carbides, nitrides, phosphides and silicides)" with the idealized chemical composition CuAl and is therefore chemically a natural alloy of copper and aluminum in Mole ratio of 1: 1.

Naturally formed cupalite crystallizes in the orthorhombic crystal system and develops myrmekitic (worm-shaped) to dendritic or teardrop-shaped grains of up to 35 μm in size as inclusions in khatyrkite and irregularly shaped grains of up to 20 μm in size in cracks of the khatyrkite.

The mineral is opaque in every form and has a metallic sheen on the surfaces of the gray-yellow grains .

Etymology and history

Cupalite was first discovered in a fragment of the Khatyrka meteorite , of which a total of ten pieces could be found on the Chatyrka River ( Khatyrka in English ) in the Koryak Autonomous Okrug in the far east of Russia . The meteorite is therefore considered to be the type locality of the mineral.

The analysis and first description of cupalite was carried out in 1985 by LV Razin, NS Rudashevskij and LN Vyalsov, who named the mineral after its composition of copper and aluminum .

classification

In the outdated, but still in use 8th edition of the mineral classification according to Strunz , the cupalite belonged to the mineral class of "elements" and there to the department of "metals and intermetallic alloys (without semi-metals)", where together with aluminum and khatyrkite it belongs to the unnamed group I. /A.03 formed.

The 9th edition of Strunz's mineral systematics , which has been in effect since 2001 and is used by the International Mineralogical Association (IMA), also assigns cupalite to the “Metals and Intermetallic Compounds” department. 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. According to its composition, Cupalit can be found here as namesake together with copper in the subdivision "Copper Cupalit Family", where it is the only member of the unnamed group 1.AA.20 .

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the cupalite to the class and there in the department of the same name of "elements". Here he can be found together with Khatyrkit in the unnamed group 01.01.15 within the sub-section "Elements: Metallic elements other than the platinum group".

Chemism

Using nine grains with the help of electron beam microanalysis , Razin, Rudashevskij and Vyalsov were able to determine the chemical composition with a weight percentage of 59.9 to 61.7% copper, 29.3 to 30.4 & aluminum and 7.66 to 9.35% zinc (Total 98.61 to 100.45%) with a negative correlation between copper and zinc. The measurement results correspond to the empirical formula (Cu, Zn) Al.

Crystal structure

The X-ray diffraction using the powder diffraction showed that the mineral has an orthorhombic symmetry. The lattice parameters are a = 6.95 (1)  Å , b = 4.16 (1) Å and c = 10.04 (1) Å with 10 formula units per unit cell . However, the exact space group could not be determined. The X-ray pattern should resemble that of synthetic CuAl 2 and show a centered orthorhombic cell. The strongest of the seven determined X-ray reflections are 5.07 (10) (002), 4.12 (8) (010), 3.59 (2) (110).

In 1972 Mohamed El-Boragy, Reiner Szepan and Konrad Schubert analyzed two synthetically produced samples with the idealized composition of cupalite (CuAl) and came to the conclusion that this compound crystallizes in a monoclinic manner and either has the space group I 2 / m (space group No. 12 , Position 3) with the lattice parameters a  = 9.889  Å ; b  = 4.105 Å; c  = 6.913 Å and β = 89.996 ° or the C 2 / m (No. 12) with the lattice parameters a  = 12.066 Å; b  = 4.105 Å; c  = 6.913 Å and β = 55.04 °. Template: room group / 12.3 Template: room group / 12

Education and Locations

Apart from its type locality, the fragments of the meteorite Khatyrka, which were collected in the fluvial sediments along the rivers Chatyrka and Listventovyi (also Listvenitovyi ), no other location for cupalite is known so far (as of March 2018).

See also

literature

  • LV Razin, NS Rudashevskij, LN Vyalsov: New natural intermetallic compounds of aluminum, copper and zinc - Cupalite CuAl, cupalite CuAl and zinc aluminides - from hyperbasites of dunite-harzburgite formation . In: Zapiski Vsesoyuznogo Mineralogicheskogo Obshchestva . tape 114 , no. 1 , 1985, pp. 90-100 (Russian).
  • Frank C. Hawthorne, Michael Fleischer, Edward S. Grew, Joel D. Grice, John L. Jambor, Jacek Puziewicz, Andrew C. Roberts, David A. Vanko, Janet A. Zilczer: New Minerals . In: American Mineralogist . tape 71 , no. 9-10 , 1986, pp. 1277–1282 ( minsocam.org [PDF; 793 kB ; accessed on March 11, 2018]).
  • Mohamed El-Boragy, Reiner Szepan, Konrad Schubert: Crystal structure of Cu 3 Al 2+ (h) and CuAl (r) . In: Journal of the Less Common Metals . tape 29 , no. 2 , October 1972, p. 133-140 , doi : 10.1016 / 0022-5088 (72) 90183-X .

Web links

Individual evidence

  1. ^ A b 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.  36 .
  2. ^ IMA / CNMNC List of Mineral Names; November 2017 ( Memento from April 17, 2018 in the Internet Archive ) (PDF 1.67 MB)
  3. ↑ 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 .
  4. ↑ a b c Cupalite . 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; 351  kB ; accessed on March 11, 2018]).
  5. ^ A b Frank C. Hawthorne, Michael Fleischer, Edward S. Grew, Joel D. Grice, John L. Jambor, Jacek Puziewicz, Andrew C. Roberts, David A. Vanko, Janet A. Zilczer: New Minerals . In: American Mineralogist . tape 71 , no. 9-10 , 1986, pp. 1277–1282 ( minsocam.org [PDF; 793 kB ; accessed on March 11, 2018]).
  6. ↑ Mohamed El-Boragy, Reiner Szepan, Konrad Schubert: Crystal structure of Cu 3 Al 2+ (h) and CuAl (r) . In: Journal of the Less Common Metals . tape 29 , no. 2 , October 1972, p. 133-140 , doi : 10.1016 / 0022-5088 (72) 90183-X .
  7. ↑ List of localities for cupalite in the Mineralienatlas and Mindat