“Danburite,” Charcas, Mun. de Charcas, San Luis Potosí, Mexico. © Rob Lavinsky, www.iRocks.com. Used with permission.
A hard and durable gemstone, danburite is an excellent choice for jewelry wear. Although the mineral isn't rare, large facetable pieces are scarce. Still, sufficient material exists for gem enthusiasts and adventurous jewelry lovers to add this lovely and under appreciated stone to their collections.
Danburite Value
Tried and true gem value factors apply to danburite. All other things being equal, larger, cleaner, better cut and better colored stones have a higher value per carat. However, a truly colorless specimen would surpass a very pale yellow or slightly pink stone in value per carat.
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Danburite Information
| Data | Value |
| Name | Danburite |
| Crystallography | Orthorhombic; Crystals prismatic with wedge-shaped terminations, like topaz. |
| Refractive Index | 1.627 - 1.641 |
| Colors | Colorless, white, pink, light to dark yellow, yellowish brown, brown. |
| Luster | Vitreous to greasy. |
| Fracture | Fracture subconchoidal to uneven. Brittle. |
| Hardness | 7 |
| Specific Gravity | 2.97-3.03, usually 3.00. |
| Birefringence | 0.006-0.008 |
| Cleavage | Indistinct |
| Dispersion | 0.017 |
| Luminescence | Sky blue to bright blue-green in LW. Also, thermoluminescent (red). |
| Spectral | Sometimes shows rare earth spectrum, so-called didymium lines. |
| Wearability | Excellent |
| Enhancements | None Known |
| Transparency | Trasparent |
| Formula | CaB2Si2O8 |
| Pleochroism | None |
| Optics | a = 1.630-1.633; β = 1.633-1.637; γ = 1.636-1.641. Biaxial (-); 2V= 88° in red to green light; optically (+) at lower wavelengths. |
| Etymology | After the type locality, Danbury, Connecticut. |
| Occurrence | In dolomites; in carbonate veins in granitic rocks. |
| Inclusions | Fingerprints (healed fractures), hollow growth tubes. |
Danburite: Charcas, Mexico (8.5, crystal ~ 2 1⁄2 inches long). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Comments
Danburite’s colors range from colorless to light yellow or pale pink to tan. With poor cleavage and a hardness of seven, it catches popular jewelry stones such as quartz and topaz in toughness. Although its modest dispersion means cut danburites lack fire, properly cut gems are very bright.
Identifying Characteristics
Interestingly, most specimens fluoresce a sky blue color in longwave ultraviolet light and phosphoresce red when heated.
“Danburite from Type Locality,” mass with crude crystal faces, Danbury, Fairfield Co., Connecticut, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.
Synthetics
No known enhancements, synthetics, or imitations on the market.
Sources
First discovered in Danbury, Connecticut, danburite has been found and mined in Japan, Madagascar, Mexico, and Myanmar. Notable locations include:
- United States: Danbury, Connecticut, type locality.
- Japan: Obira, Bungo, Kyushu, colorless crystals, sometimes gemmy.
- Madagascar: yellow crystals at Mt. Bity, often gemmy.
- Mexico: Charcas, San Luis Potosí, colorless, yellow, light pink (gemmy).
- Myanmar: Mogok, yellow and colorless, sometimes large crystals (rolled pebbles).
- Russia: colorless, gemmy material.
- Bolivia; China; Tanzania.
“Danburite,” Sakangyi, Mogok Township, Mandalay Division, Myanmar. © Rob Lavinsky, www.iRocks.com. Used with permission.
Stones Sizes
Danburites, especially colorless material from Mexico, typically range in size between 1 and 5 carats. Yellow gems from Myanmar between 7 and 10 carats are very rare today.
- British Museum of Natural History (London): Myanmar, wine-yellow, step-cut, flawless, 135.61.
- Smithsonian Institution (Washington, D.C): 18.4 (Myanmar, yellow) 12.4; 10.5 (Mexico, colorless); 7.9 (Japan, colorless).
- Los Angeles County Museum (Los Angeles): Madagascar, brownish, emerald cut, 115.
- Royal Ontario Museum (Toronto, Canada): Russia, colorless, step-cut, 12.72.
- Private Collections: 20 (Myanmar, peach color); 22.76 (Madagascar, yellow); 37 (Russia).
“Danburite,” Merelani Hills, Arusha Region, Tanzania. © Rob Lavinsky, www.iRocks.com. Used with permission.
Care
Due to some heat sensitivity, avoid steam cleaning this gem. Otherwise, danburite requires no special care. You can use these gems for all jewelry applications, including rings and bracelets. Consult our gemstone jewelry cleaning guide for more care recommendations.
“Cut Danburite,” Locality: Anjanabonoina, Ikaka, Ambohimanambola Commune, Betafo District, Vakinankaratra Region Antananarivo Province, Madagascar (0.47 cts), by Didier Descouens. Licensed under CC By-SA 4.0.
