Hafnon forms a
solid-solution series with its
zirconium counterpart,
zircon (). Several other variants exist, with compositions such as . In nature, part of
zirconium is replaced by the chemically similar hafnium, so natural zircon is never pure . 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. Hafnon occurs naturally in
tantalum-bearing
granite pegmatites in
Zambezia (Mozambique), and in weathered
pegmatites at Mount Holland,
Western Australia. It has also been reported at locations in
Ontario,
Quebec, and
Manitoba, Canada;
North Carolina, United States, and
Zimbabwe. ==References==