Hafnon

Hafnon
Very small brown single crystals of hafnon from Bernic Lake, Lac-du-Bonnet District, Manitoba, Canada
General
Category	Nesosilicates
Formula (repeating unit)	HfSiO4
IMA symbol	Haf [1]
Strunz classification	09.AD.30
Dana classification	51.05.02.02
Crystal system	Tetragonal
Crystal class	Ditetragonal Dipyramidal (4/mmm ) H-M symbol: (4/m 2/m 2/m)
Space group	I41/amd
Unit cell	a = 6.5725(7) Å, c = 5.9632(4) Å=; Z = 4
Identification
Colour	Orange-red,brownish yellow, rarely colourless
Crystal habit	Euhedral to irregular crystals
Cleavage	{???} Indistinct
Mohs scale hardness	7.5
Luster	Vitreous
Streak	grey white
Diaphaneity	Transparent
Density	6.97
Optical properties	Uniaxial (+)
Refractive index	nω = 1.930 - 1.970 nε = 1.980 - 2.030
Birefringence	δ = 0.050
Common impurities	Often zoned with zircon. Forms part of zircon-hafnon series

Hafnon is a hafnium nesosilicate mineral with the idealized chemical formula HfSiO₄. It is the mineral form of Hafnium silicate and one of the few known minerals with essential hafnium.

Chemistry

Hafnon forms a solid solution series with its zirconium counterpart, zircon (ZrSiO₄). Several more

or (Hf,Zr,Th,U,Y)SiO₄. ^[2] In natural 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 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

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. 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

• Emsley, John. Nature's Building Blocks. Oxford, 2001. ISBN   0-19-850341-5
• J. A. Speer, B. J. Cooper (1982). "Crystal structure of synthetic hafnon, HfSiO₄, comparison with zircon and the actinide orthosilicates" (PDF). American Mineralogist . 67: 804–808.