Hambergite
Hambergite is Be2(BO3)(OH), an orthorhombic beryllium borate of granite pegmatites: hardness 7.5, density 2.347–2.372, birefringence about 0.07. Its numbers.
Hambergite is Be2(BO3)(OH) on the September 2026 IMA list: an orthorhombic beryllium borate, an uncommon accessory mineral in granite pegmatites, colourless to pale gray or yellow, hardness 7.5 but density only 2.347–2.372. Worked, it is 19.21% beryllium. Its birefringence, about 0.07, is eight times quartz’s on a stone lighter than quartz.
In short
- The species. The Handbook of Mineralogy sheet gives orthorhombic crystals, typically well crystallized, prismatic along [001] or dipyramidal, to 30 cm, with twins on {110}; perfect {010} and good {100} cleavage; hardness 7.5; density 2.347–2.372; colourless, pale gray or pale yellow; vitreous; biaxial (+). The September 2026 IMA-CNMNC Master List row reads Be2(BO3)(OH), status G, 1890, Norway.
- Light but strongly doubly refracting. Worked from the sheet, γ − α is 0.074 at the low ends of the ranges and 0.071 at the high ends; quartz’s is 0.009. Of the eight colourless pegmatite species in the table below, hambergite has both the lowest density and the highest birefringence, by script. A 20.00 g piece reads 11.48–11.57 g in water, about 0.9 g below quartz’s 12.45 g, though it is harder than quartz.
- Documented failure: the B2O5 line. The sheet’s chemistry column prints the boron oxide as “B2O5”. Its own analysis formulas carry one boron to three oxygens, and worked as B2O3 the Little Three formula gives BeO 52.97, B2O3 36.86, F 6.04, H2O 6.68 and −O = F2 2.54, against the printed 52.9, 36.6, 6.0, 6.7 and 2.5. As B2O5 the boron oxide would be 53.80%. The column is B2O3.
- The most beryllium on the shelf. At 19.21% by mass, hambergite carries more beryllium than phenakite (16.37%), bertrandite (15.13%), beryllonite (7.10%) or beryl (5.03%), worked from the IMA formulas. Beryllium-bearing dust is a hazard question this page does not answer; it is routed to toxic minerals in a collection, and nothing here is advice.
- Where it is found. The sheet’s Distribution opens at Helgeroa, Langesundsfjord, Norway, then the Czech Republic, Elba, Madagascar (large crystals from Anjanabanoana), California (Little Three and Himalaya mines, Jensen quarry), Nevada, Wisconsin, Pakistan (around Stak Nala and Drot, on the Gilgit–Skardu road), Tajikistan and Russia.
| Species | IMA formula | Hardness | Density (sheet) | 20.00 g in water | Indices (sheet) | Birefringence, worked | Be by mass |
|---|---|---|---|---|---|---|---|
| Hambergite | Be2(BO3)(OH) | 7.5 | 2.347–2.372 | 11.48–11.57 g | α 1.554–1.560, γ 1.628–1.631 | 0.071–0.074 | 19.21% |
| Bertrandite | Be4Si2O7(OH)2 | 6–7 | 2.59–2.60 | 12.28–12.31 g | α 1.583–1.591, γ 1.608–1.614 | 0.023–0.025 | 15.13% |
| Quartz | SiO2 | 7 | 2.65 | 12.45 g | ω 1.544, ε 1.553 | 0.009 | None |
| Beryllonite | NaBe(PO4) | 5.5–6 | 2.77–2.84 | 12.78–12.96 g | α 1.552, γ 1.561 | 0.009 | 7.10% |
| Beryl | Be3Al2(Si6O18) | 7.5–8 | 2.63–2.97 | 12.40–13.27 g | ω 1.567–1.610, ε 1.565–1.599 | 0.002–0.011 | 5.03% |
| Phenakite | Be2(SiO4) | 7.5–8 | 2.93–3.00 | 13.17–13.33 g | ω 1.650–1.656, ε 1.667–1.670 | 0.014–0.017 | 16.37% |
| Danburite | CaB2Si2O8 | 7–7.25 | 2.93–3.02 | 13.17–13.38 g | α 1.627–1.633, γ 1.633–1.639 | 0.006 | None |
| Topaz | Al2SiO4F2 | 8 | 3.49–3.57 | 14.27–14.40 g | α 1.606–1.634, γ 1.616–1.644 | 0.010 | None |
What is hambergite? A beryllium borate of granite pegmatites
Hambergite is Be2(BO3)(OH), an orthorhombic beryllium borate that its sheet calls an uncommon accessory mineral in granite pegmatites. The Handbook of Mineralogy hambergite sheet heads it Be2BO3(OH,F) and describes crystals that are typically well crystallized, prismatic along [001] or dipyramidal, showing {110}, {021}, {010}, {100} and {210} with another 20 forms known, {100} striated parallel to [001], to 30 cm. Twins on {110} are commonly reticulated, and contact twins may be markedly hemimorphic. Cleavage is perfect on {010} and good on {100}; it is brittle, hardness 7.5, density 2.347–2.372.
What the lists record. The September 2026 IMA-CNMNC Master List writes Be2(BO3)(OH), status G, 1890, country Norway, with a second reference in American Mineralogist 97 (2012). A script over the list finds one other row made of beryllium, borate and hydroxyl alone: berborite, Be2(BO3)(OH)(H2O), approved 1967, Russia, the same formula with a water molecule added. It finds no fluorine-dominant hambergite row. The name honours Professor Axel Hamberg (1863–1933), Swedish mineralogist and geographer (sheet). Type material is held by museums in Sweden, France and the USA; the sheet marks no type locality (what a type locality is).
Fluorine, worked. The sheet’s analyses correspond to Be2.04B0.98O3[(OH)0.93F0.05] from Anjanabanoana, Madagascar, and Be2.00B1.00O3[(OH)0.70F0.30] from the Little Three mine, California. Worked, the Little Three formula is 6.04% fluorine, the printed 6.0. Both analyses are hydroxyl-dominant, which is why the IMA formula carries OH alone.
Why is hambergite so easy to recognise? Birefringence against weight
It combines a hardness above quartz with a density well below it and a birefringence about eight times quartz’s. The sheet’s indices are α 1.554–1.560, β 1.587–1.591, γ 1.628–1.631: γ − α is 0.074 at the low ends and 0.071 at the high ends. Quartz’s is 0.009, danburite’s 0.006, topaz’s 0.010, phenakite’s 0.014–0.017. Of the eight species in the table, all from the same kind of rock, hambergite has the lowest density and the highest birefringence; the script checked both over those eight rows and no wider set.
The weighing. A 20.00 g piece of hambergite reads 11.48–11.57 g in water; quartz reads 12.45 g, bertrandite 12.28–12.31 g and beryllonite 12.78–12.96 g. Nothing in the table comes within 0.7 g of hambergite. The method is on how to measure specific gravity at home.
What the gem trade says. The International Gem Society hambergite page calls hambergite a gem for collectors of the unusual, gives birefringence 0.072 and specific gravity 2.35–2.37, in line with the sheet, and says its cleavage can make faceting difficult. It also writes that hambergite has the lowest known specific gravity of any gem with such high birefringence; that is the society’s claim, and this page’s check covers only the eight rows above.
Documented failure: why the sheet’s B2O5 must be B2O3
The chemistry column prints the boron oxide as B2O5, a formula boron does not take in this mineral. The rendered sheet shows “B2O5” over 36.0 and 36.6. The sheet’s own formulas, Be2.04B0.98O3 and Be2.00B1.00O3, carry three oxygens with each boron, which is B2O3 when written as an oxide.
The arithmetic decides. Worked as B2O3 on standard atomic weights, the Little Three formula Be2B O3[(OH)0.70F0.30] gives BeO 52.97, B2O3 36.86, F 6.04, H2O 6.68 and −O = F2 2.54; the printed analysis is 52.9, 36.6, 6.0, 6.7 and 2.5. Worked as B2O5 the boron line would be 53.80%, nowhere near 36.6. For the pure IMA end member the ideal column would be BeO 53.31, B2O3 37.09 and H2O 9.60, summing to 100.00.
The cell. The sheet prints cell ranges rather than one cell. Eight formula units of 93.84 g/mol give 2.390 in the smallest printed cell and 2.323 in the largest, bracketing the printed calculated 2.365 and the measured 2.347–2.372. This page reads that as a range, not a check of one specimen.
Where is hambergite found? Norway, Madagascar, California and Pakistan
The hambergite sheet’s Distribution, as printed. From Helgeroa, Langesundsfjord, Norway. In the Czech Republic, from Ctidružice; Recice; Kracovice, near Tribic; Sušice; and elsewhere. From between San Ilario and San Piero in Campo, Elba, Italy. In Madagascar, from Imalo, near Mania; at Maharitra, on Mt. Bity; and large crystals from Anjanabanoana. In the USA, fine crystals from the Little Three mine, near Ramona, and the Himalaya mine, Mesa Grande district, San Diego Co., and the Jensen quarry, Riverside Co., California; large crystals from the Zapot pegmatite, 25 km northeast of Hawthorne, Mineral Co., Nevada; the Animikie Red Ace pegmatite, near Pine River, Florence Co., Wisconsin. In Pakistan, around Stak Nala and Drot, Gilgit–Skardu road, Northern Areas. The Rangkul pegmatite field, eastern Pamir Mountains, Tajikistan. In Russia, the Mokrusha mine, Ural Mountains, and the Malkhan pegmatite field, Chite region, Transbaikal. We add no other locality.
What it grows with. The sheet’s association line is beryl, danburite, apatite, spodumene, zircon, fluorite, feldspar and quartz. Its reference list includes Richards (1996) on twinned hambergite from the Gilgit district of northern Pakistan. beryl and spodumene have their own pages in the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.