Zhanghengit

Zhanghengit
	Golden yellow Zhanghengit crystal from an unspecified "gold" deposit in North Vietnam (size: 1.25 mm × 0.62 mm × 0.50 mm)
General and classification
other names	IMA 1985-049
chemical formula	β-CuZn
Mineral class; (and possibly department)	elements
System no. to Strunz ; and to Dana	1.AB.10a ( 8th edition : I / A.04) ; 01.01.06.02
Crystallographic Data
Crystal system	cubic
Crystal class ; symbol	cubic hexakisoctahedral; 4 / m 3 2 / m
Space group	In 3 m (No. 229)
Lattice parameters	a = 2.95 Å
Physical Properties
Mohs hardness	3.5 ( VHN 10 = 140 to 150)
Density (g / cm 3 )	calculated: 8.32 (synthetic)
Cleavage	is missing
colour	golden yellow
Line color	bronze colored
transparency	opaque (opaque)
shine	Metallic luster

Zhanghengit is a very rarely occurring minerals from the mineral class of "elements (including natural alloys, intermetallic compounds, carbides, nitrides, phosphides and silicides)" with the idealized chemical composition of β-CuZn and is thus chemically seen a natural brass - alloy of copper and zinc in a molar ratio of 1: 1.

Zhanghengite crystallizes in the cubic crystal system , more precisely in the body-centered cubic (krz) lattice, but has so far only been found in the form of irregular to tabular crystal grains and granular or dendritic mineral aggregates with sizes in the tenths of a millimeter.

The mineral is opaque in every form and shows a clear metallic luster on the surfaces of the golden-yellow crystal grains . The line color , on the other hand, is darker with a bronze-like tone.

Etymology and history

Zhang Heng on a Chinese postage stamp from 1955

Zhanghengite was first discovered in the Boxian meteorite , a chondrite that fell on October 20, 1977 about 120 km west-southwest of Huaibei in the Chinese province of Anhui. The mineral was first described in 1986 by Wang Kuiren (王奎仁), who chose the name in honor of the important Chinese mathematician and astronomer Zhang Heng (78-139). Zhang Heng lived during the Han Dynasty and, among other things, invented what is probably the world's first seismoscope .

A storage location for the type material (mineral samples from the type locality ) is not known.

classification

Already in the outdated, but partly still in use 8th edition of the mineral classification according to Strunz , the zhanghengite belonged to the mineral class of "elements" and there to the department of "metals and intermetallic alloys (without semimetals)", where it belongs together with cadmium , danbaite , brass , Tongxinite and zinc formed the unnamed group I / A.04 .

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 the Zhanghengit to the department of "Metals and intermetallic compounds". 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, Zhanghengit can be found in the sub-section “zinc-brass family”, where together with zinc copperite it forms the “brass group” with system no. 1.AB.10a forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , assigns the Zhanghengit to the class and department of the same name of "elements". Here he can be found together with brass and danbait in the unnamed group 01.01.06 within the sub-section "Elements: Metallic elements other than the platinum group".

Chemism

The analysis of a total of six microsamples of the type material showed that the main components were 50.46–53.68% by weight copper, 45.83–49.32% by weight zinc and 0.00–0.25% by weight as additions Chromium, 0.1l-0.16 wt% iron, 0.04-0.06 wt% aluminum and 0.00-0.01 wt% nickel. This corresponds to the empirical chemical composition Cu _1.056 Zn _0.935 Fe _0.003 Al _0.003 Cr _0.003 and the idealized formula CuZn.

Crystal structure

Zhanghengit crystallizes cubically in the space group Im 3 m (space group no. 229) with the lattice parameter a = 2.95 Å and one formula unit per unit cell . Template: room group / 229

Education and Locations

In the material samples taken from the Boxian meteorite, numerous accompanying minerals were found in addition to zhanghengite , namely biotite , calcite , chromite , dolomite , ilmenite , graphite , kamacite , corundum , solid copper , magnesioferrite , olivine , orthoclase , pentlandite , quartz , taenite , troilite , whitlockite , Wüstit and various plagioclases , clino- and orthopyroxenes .

In addition to its type locality Boxian in China, Zhanghegit has so far only been found on earth at an unspecified site in Vietnam and in rock samples of volcanic material that oozed from the river bank of the Mahanadi in 2002 .

In addition, the mineral could still be proven in rock samples from the moon that the crew of the Luna 20 mission brought from the Apollonius crater .

literature

Kuiren Wang: Zhanghengite - A new mineral . In: Acta Mineralogica Sinica . tape 6 , 1986, pp. 220–223 (Chinese with a brief description in English).
John Leslie Jambor , Edward S. Grew: New Mineral Names . In: American Mineralogist . tape 75 , 1990, pp. 240–246 ( minsocam.org [PDF; 910 kB ; accessed on July 9, 2019]).
Richard V. Gaines, H. Catherine W. Skinner, Eugene E. Foord, Brian Mason , Abraham Rosenzweig: Dana's New Mineralogy . 8th edition. John Wiley & Sons, New York (et al.) 1997, ISBN 0-471-19310-0 , pp. 7 .
B. Mallick1, TR Rautray, PK Nayak, V. Vijayan, P. Singh, RC Behera, T. Patel, RK Choudhury: Characterization of hot material erupted from Mahanadi Riverbank using EDXRF and XRD techniques . In: Indian Journal of Physics . tape 79 , no. 3 , March 2005, p. 293–296 ( available online at researchgate.net ).

Web links

Commons : Zhanghengite - collection of pictures, videos and audio files

Mineral Atlas: Zhanghengit (Wiki)
Zhanghengite. In: mindat.org. Hudson Institute of Mineralogy, accessed July 9, 2019 .

Individual evidence

↑ ^a ^b ^c ^d 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. 37 .
↑ David Barthelmy: Zhanghengite Mineral Data. In: webmineral.com. Retrieved July 9, 2019 .
↑ ^a ^b ^c ^d 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 .
^ ^A ^b ^c ^d John Leslie Jambor , Edward S. Grew: New Mineral Names . In: American Mineralogist . tape 75 , 1990, pp. 240–246 ( minsocam.org [PDF; 910 kB ; accessed on July 9, 2019]).
↑ Type locality Boxian Meteorite, Xiaoyanzhuang, Qiaocheng District, Bozhou Prefecture, Anhui Province, China. In: mindat.org. Hudson Institute of Mineralogy, accessed July 9, 2019 .
↑ ^a ^b List of locations for Zhanghengit in the Mineralienatlas and Mindat

[StrunzNickel-1] 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. 37 .

[Webmineral-2] David Barthelmy: Zhanghengite Mineral Data. In: webmineral.com. Retrieved July 9, 2019 .

[Lapis-3] 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 .

[JamborGrew-4] A ^b ^c ^d John Leslie Jambor , Edward S. Grew: New Mineral Names . In: American Mineralogist . tape 75 , 1990, pp. 240–246 ( minsocam.org [PDF; 910 kB ; accessed on July 9, 2019]).

[MindatBoxian-5] Type locality Boxian Meteorite, Xiaoyanzhuang, Qiaocheng District, Bozhou Prefecture, Anhui Province, China. In: mindat.org. Hudson Institute of Mineralogy, accessed July 9, 2019 .

[Fundorte-6] List of locations for Zhanghengit in the Mineralienatlas and Mindat