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The Mineral hafnon

Hafnon is isomorphous with the mineral Zircon. It is almost identical to Zircon in physical properties, and occurs together with it. Thought to be Zircon, it is rarely identified separately when found. Because of this, Hafnon is hardly known to mineral collectors, and in reality it is much more prevalent than perceived. The name Hafnon is derived from a combination of the words hafnium and Zircon.
Chemical Formula HfSiO4
Composition Hafnium silicate, often with some zirconium and occasionally with some uranium, thorium, and yttrium. It can contain up to 45 percent of zirconium in its structure; if it exceeds that then it is no longer Hafnon but Zircon.
Variable Formula (Hf,Zr)SiO4 ;
Color Gray, brown, brownish-red, orange, black
Streak Colorless
Hardness 7.5
Crystal System Tetragonal
Crystal Forms
and Aggregates
As short, stubby crystals, and as prismatic crystals. Crystals are almost always terminated with a pyramidal termination, and are sometimes doubly terminated. Also grainy and as rounded, waterworn pebbles.
Transparency Translucent to opaque
Specific Gravity 6.97
Luster Greasy to adamantine. Radioactive Hafnon has a pitchy luster.
Cleavage 3,2
Fracture Conchoidal to uneven
Tenacity Brittle
In Group Silicates; Nesosilicates
Striking Features Crystal shape and weight
Environment In rare earth granite pegmatites and in placer deposits.
Rock Type Igneous
Popularity (1-4) 4
Prevalence (1-3) 3
Demand (1-3) 3

Hafnium Zircon Synonym of Hafnon.

Although Hafnon is not a well-known mineral, it often occurs together with Zircon rich in hafnium, and is thus an ore of the rare metal hafnium.

Hafnon occurs in every locality where there exists hafnium-rich Zircon. Since Hafnon is almost identical in physical and chemical properties to Zircon, it is rarely distinguished from it. The type locality for Hafnon is Alto Ligonha, Zambezia Province, Mozambique, where it has been found at several pegmatites at the Muiane Mine. Chestnut-colored Hafnon crystals have been found in the Naque region in Minas Gerais, Brazil.

Zircon, Monazite, Xenotime, Albite, Quartz, Biotite, Orthoclase, Nepheline

Zircon - Cannot be identified without complex tests.
Vesuvianite - Softer (6½), lighter in weight.
Cassiterite - Heavier, softer.
Spinel - Occurs in octahedral crystals, lighter in weight (3.5 - 4.1).

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