Hafnon
Hafnium neosilicate mineral
From Wikipedia, the free encyclopedia
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.
| Hafnon | |
|---|---|
Very small brown single crystals of hafnon from Bernic Lake, Lac-du-Bonnet District, Manitoba, Canada | |
| General | |
| Category | Nesosilicates |
| Formula | 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 |
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.[2][4]
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]
