Hafnon
Hafnon is a hafnium nesosilicate mineral, chemical formula (Hf,Zr)SiO
4 or (Hf,Zr,Th,U,Y)SiO
4.[1] In natural zircon ZrSiO
4 part of the zirconium is replaced by the very similar hafnium and so natural zircon is never pure ZrSiO
4. A zircon with 100% hafnium substitution can be made synthetically and is hafnon.
| Hafnon | |
|---|---|
| General | |
| Category | Nesosilicates |
| Formula (repeating unit) | Hafnium silicate (HfSiO4) |
| 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 occurs as transparent red to red orange tetragonal crystals with a hardness of 7.5.[2][3]
Hafnon occurs naturally in tantalum-bearing granite pegmatites in the Zambezia district, Mozambique and in weathered pegmatites at Mount Holland, Western Australia.[4] It has also been reported from locations in Ontario, Quebec and Manitoba, Canada; North Carolina, United States; and in Zimbabwe.[2]
References
- http://www.minerals.net/mineral/silicate/neso/zircon/hafnon.htm Minerals.net
- http://www.mindat.org/min-1792.html Mindat
- "Hafnon Mineral Data". webmineral.com. Retrieved 2021-01-31.
- http://www.handbookofmineralogy.org/pdfs/Hafnon.PDF 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.
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