Hafnon is a hafnium nesosilicate mineral, chemical formula (Hf,Zr)SiO4 or (Hf,Zr,Th,U,Y)SiO4.[2] In natural zircon ZrSiO4 part of the zirconium is replaced by the very similar hafnium and so natural zircon is never pure ZrSiO4. A zircon with 100% hafnium substitution can be made synthetically and is hafnon.

Hafnon
Very small brown single crystals of hafnon from Bernic Lake, Lac-du-Bonnet District, Manitoba, Canada
General
CategoryNesosilicates
Formula
(repeating unit)
Hafnium silicate (HfSiO4)
IMA symbolHaf[1]
Strunz classification09.AD.30
Dana classification51.05.02.02
Crystal systemTetragonal
Crystal classDitetragonal Dipyramidal (4/mmm )
H-M symbol: (4/m 2/m 2/m)
Space groupI41/amd
Unit cella = 6.5725(7) Å, c = 5.9632(4) Å=; Z = 4
Identification
ColourOrange-red,brownish yellow, rarely colourless
Crystal habitEuhedral to irregular crystals
Cleavage{???} Indistinct
Mohs scale hardness7.5
LusterVitreous
Streakgrey white
DiaphaneityTransparent
Density6.97
Optical propertiesUniaxial (+)
Refractive indexnω = 1.930 - 1.970 nε = 1.980 - 2.030
Birefringenceδ = 0.050
Common impuritiesOften zoned with zircon. Forms part of zircon-hafnon series

Hafnon occurs as transparent red to red orange tetragonal crystals with a hardness of 7.5.[3][4]

Hafnon occurs naturally in tantalum-bearing granite pegmatites in the Zambezia district, Mozambique and in weathered pegmatites at Mount Holland, Western Australia.[5] It has also been reported from locations in Ontario, Quebec and Manitoba, Canada; North Carolina, United States; and in Zimbabwe.[3]

References

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  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ http://www.minerals.net/mineral/silicate/neso/zircon/hafnon.htm Minerals.net
  3. ^ a b http://www.mindat.org/min-1792.html Mindat
  4. ^ "Hafnon Mineral Data". webmineral.com. Retrieved 2021-01-31.
  5. ^ http://www.handbookofmineralogy.org/pdfs/Hafnon.PDF Archived 2021-10-20 at the Wayback Machine Handbook of Mineralogy