Hafnon

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Hafnon
General and classification
other names

IMA 1974-018

chemical formula Hf [SiO 4 ]
Mineral class
(and possibly department)
Silicates and Germanates
System no. to Strunz
and to Dana
9.AD.30 ( 8th edition : VIII / A.09)
05.51.02.02
Crystallographic Data
Crystal system tetragonal
Crystal class ; symbol ditetragonal-dipyramidal; 4 / m 2 / m 2 / m
Room group (no.) I 4 1 / amd (No. 141)
Lattice parameters a  = 6.57  Å ; c  = 5.96 Å
Formula units Z  = 4
Physical Properties
Mohs hardness 7 to 7.5
Density (g / cm 3 ) calculated: 6.97 (synthetic)
Cleavage indistinct
colour orange-red, brownish-yellow, rarely colorless
Line color White
transparency transparent to translucent
shine Glass gloss to diamond gloss
Crystal optics
Refractive indices n ω  = 1.930 to 1.970
n ε  = 1.980 to 2.030
Birefringence δ = 0.050
Optical character uniaxial positive

Hafnon is a very rarely occurring mineral from the mineral class of " silicates and germanates ". It crystallizes in the tetragonal crystal system with the chemical composition Hf [SiO 4 ] and thus a hafnium silicate. Hafnon is also the only known mineral to date with hafnium as the main component. Structurally, hafnon belongs to the island silicates and is closely related to zirconium (Zr [SiO 4 ]).

Hafnon develops idiomorphic to irregular crystals and fragments with a glass-like to diamond-like sheen on the surfaces. In its pure form, Hafnon is colorless and transparent. However, due to foreign admixtures , it usually takes on an orange-red to brownish-yellow color, with a decrease in transparency.

Etymology and history

Hafnon was discovered for the first time in various mineral samples from the "Moneia" and "Morro Conco" pits as well as in the Muiâne pegmatites near Alto Ligonha in the Zambezia province in Mozambique . The mineral was first described in 1974 by JM Correia Neves, JEL Nunes, Th. G. Sahama, who named it after its main component, hafnium, with the ending -on indicating its close relationship with zircon.

classification

Already in the outdated, but partly still in use 8th edition of the mineral systematics according to Strunz , the Hafnon belonged to the mineral class of "silicates and germanates" and there to the department of " island silicates (nesosilicates)", where it was used together with coffinite , reidite , thorite , thorogummite and zircon the " zircon group" with the system no. VIII / A.09 .

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 classifies Hafnon in the category of "island silicates (nesosilicates)". However, this is further subdivided according to the possible presence of further anions and the coordination of the cations involved , so that the mineral is classified in the sub-section “Island silicates without additional anions; Cations in octahedral [6] and usually larger coordination "can be found, where the" zircon group "with the system no. Is also found together with coffinite, steadindite , thorite, thorogumite and zirconium. 9.AD.30 forms.

The systematics of minerals according to Dana , which is mainly used in the English-speaking world , also classifies the Hafnon in the category of "island silicates". Here it is also in the " zircon group " with system no. May 51, 2002 to be found in the subsection “ Island silicates: SiO 4 groups only with cations in> [6] coordination”.

Education and Locations

Hafnon forms in tantalum-containing and weathered granite - pegmatites . As Begleitminerale among others can albite , anthophyllite , apatite , Bismoclit , Bartyt , beryl , Cesstibtantit , cookeite , potassium- feldspar , Ferrocolumbit , cassiterite , Kimrobinsonit , Manganotantalit , Mikrolith , muscovite , phlogopite , quartz , thorite, tourmaline and zircon occur.

As a rare mineral formation, Hafnon could only be proven at a few sites, whereby so far (as of 2013) a little more than 10 sites are known. The area around Alto Ligonha is the only known site in Mozambique to date.

Other previously known sites are the Forrestania rubellite pegmatites in the Yilgarn shire administrative area in Australia, the Tanco mine in the Manitoba province and the Leduc mine in the Quebec province in Canada, Sidi Bou Othmane in the Moroccan province of Rehamna , the Bikita mine Pegmatite in Masvingo Province in Zimbabwe and the Ray Mica Mine (Wray Mine) on Hurricane Mountain near Burnsville (North Carolina) in the USA.

Crystal structure

Hafnon crystallizes isotypically with zircon in the tetragonal crystal system in the space group I 4 1 / amd (space group no. 141) with the lattice parameters a  = 6.57  Å and c  = 5.96 Å as well as four formula units per unit cell .

See also

literature

  • JM Correia Neves, JEL Nunes, Th. G. Sahama: High hafnium members of the zircon-hafnon series from the granite pegmatites of Zambézia, Mozambique. In: Contributions to Mineralogy and Petrology. 48: 73-80 (1974)
  • M. Fleischer, A. Pabst, JA Mandarino, GY Chao, LJ Cabri: New Mineral Names. In: American Mineralogist. Volume 61 (1976), pp. 174-186 ( PDF 1.55 MB , p. 2)

Web links

Individual evidence

  1. a b c d e Hugo Strunz , Ernest H. Nickel: Strunz Mineralogical Tables . 9th edition. E. Schweizerbart'sche Verlagbuchhandlung (Nägele and Obermiller), Stuttgart 2001, ISBN 3-510-65188-X , p.  543 .
  2. a b Webmineral - Hafnon
  3. Stefan Weiß: The large Lapis mineral directory. All minerals from A - Z and their properties . 5th completely revised and supplemented edition. Weise, Munich 2008, ISBN 978-3-921656-70-9 .
  4. ^ Hafnon , In: John W. Anthony, Richard A. Bideaux, Kenneth W. Bladh, Monte C. Nichols (eds.): Handbook of Mineralogy, Mineralogical Society of America , 2001 ( PDF 64 kB )
  5. a b Mindat - Hafnon
  6. Webmineral - Mineral Species sorted by the element Hf (Hafnium)
  7. Mindat - Number of localities for Hafnon
  8. Find location list for Hafnon in the Mineralienatlas and in Mindat
  9. ^ Friedrich Klockmann : Klockmanns textbook of mineralogy . Ed .: Paul Ramdohr , Hugo Strunz . 16th edition. Enke , Stuttgart 1978, ISBN 3-432-82986-8 , pp.  671 (first edition: 1891).