| Hafnon | |
|---|---|
 Very small brown single crystals of hafnon from Bernic Lake, Lac-du-Bonnet District, Manitoba, Canada | |
| General | |
| Category | Nesosilicates |
| Formula | HfSiO4 |
| IMA symbol | Haf1 |
| 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 HfSiO4.2 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 other variants exist, with compositions such as (Hf,Zr,Th,U,Y)SiO4.3 In nature, part of zirconium is replaced by the chemically similar hafnium, so natural zircon is never pure ZrSiO4. However, a zircon with 100% hafnium substitution can be synthesized and is known as hafnon.
Hafnon occurs as transparent red to red-orange tetragonal crystals, with a Moh's hardness of 7.5.24
Hafnon occurs naturally in tantalum-bearing granite pegmatites in Zambezia (Mozambique), and in weathered pegmatites at Mount Holland, Western Australia.5 It has also been reported at locations in Ontario, Quebec, and Manitoba, Canada; North Carolina, United States, and Zimbabwe.2
References
References
- 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.
- "Hafnon". www.mindat.org. Retrieved 2025-08-13.
- http://www.minerals.net/mineral/silicate/neso/zircon/hafnon.htm Minerals.net
- "Hafnon Mineral Data". webmineral.com. Retrieved 2021-01-31.
- 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.