Although hard enough for jewelry use, rare hambergite is a gem for collectors of the unusual. Its combination of high birefringence and very low specific gravity makes it easy to identify.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
|Crystallography||Orthorhombic. Crystals prismatic, flattened.|
|Colors||Colorless, white, grayish white, yellowish white.|
|Luster||Vitreous to dull.|
|Fracture||Conchoidal to uneven. Brittle.|
|Cleavage||Perfect 1 direction.|
|Luminescence||None in most specimens.|
|Transparency||Translucent to transparent.|
|Optics||a = 1.55; β= 1.59; γ= 1.63. Biaxial (+), 2V= 87°|
|Etymology||After Axel Hamberg, Swedish mineralogist, who called attention to the mineral.|
|Occurrence||In syenite pegmatites and alkali pegmatites, in crystals up to 2 x 1 inch.|
Hambergite has the lowest known specific gravity of any gem with such high birefringence. As a result, larger size stones will show significant birefringent effects without much additional weight. Although hambergites have little fire and may resemble quartz gems, their birefringence is much higher than similar-appearing gemstones.
Anjanabanoana, Madagascar produces large, gemmy crystals.
Other significant sources of crystals include:
- Afghanistan; Ramona, California; Czech Republic; India; Langesundsfjord, Norway; Pakistan; Tajikistan.
Hambergite is a fairly rare mineral. Material transparent enough to facet is rarer still. In 1968, a dealer offered a white stone of 28.86 carats. Nevertheless, cut gems over 5 carats are very rare.
- Private collections: 40.20 (largest reported); also 7.6, 5.93.
This gem’s relatively high hardness (7.5) exceeds that of quartz. However, its cleavage can make faceting difficult. These stones would more likely reside in mineral collections than on jewelry pieces. Although hambergite requires no special care, consult our gemstone jewelry cleaning guide for more recommendations.