PROFILPELAJAR.COM

Hafnon
Hafnon
	Very small brown single crystals of hafnon from Bernic Lake, Lac-du-Bonnet District, Manitoba, Canada
General
Category	Nesosilicates
Formula; (repeating unit)	Hafnium silicate (HfSiO4)
IMA symbol	Haf
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, chemical formula (Hf,Zr)SiO₄ or (Hf,Zr,Th,U,Y)SiO₄.^[2] In natural zircon ZrSiO₄ 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]