“Boracite,” Kalkberg Hill, Luneburg, Lower Saxony, Germany, (type locality). © Rob Lavinsky, www.iRocks.com. Used with permission.
With light blue and green colors, no cleavage, and high hardness, boracite is an uncommon mineral. Unfortunately for jewelry lovers, faceted boracites are very rare.
Boracite Value
The International Gem Society (IGS) has a list of businesses offering gemstone appraisal services.
Boracite Information
| Data | Value |
| Name | Boracite |
| Crystallography | Orthorhombic. Pseudo-tetragonal. Crystals small and equant. |
| Colors | Colorless, white, gray, yellow, pale to dark green, blueish green. |
| Luster | Vitreous. |
| Fracture | Conchoidal to uneven. |
| Hardness | 7-7.5. |
| Specific Gravity | 2.95 |
| Birefringence | 0.011 |
| Cleavage | None. |
| Dispersion | 0.024 |
| Luminescence | Weak greenish (SW) |
| Spectral | Not diagnostic. |
| Transparency | Translucent to transparent. |
| Formula | Mg3B7O13Cl |
| Pleochroism | None. |
| Optics | α= 1.658-1.662; β = 1.662-1.667; γ = 1.668-1.673. Biaxial (+), 2V =82°. |
| Etymology | Named after the boron in its composition. |
| Occurrence | Secondary deposits formed in evaporite sequences (seawater). |
Boracite: Hanover, Germany (0.6). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Comments
Boracite forms in salt deposits and similar environments as a result of seawater evaporation in enclosed basins. Rare cut boracites can show delicate shades of blue, green, yellow, white, and grey and have moderate dispersion. Some stones are colorless.
Identifying Characteristics
Under physical pressure, boracite generates an electric charge. This is known as known the piezoelectric effect. (Some well-known examples of piezoelectric gems include tourmaline and quartz). This mineral also exhibits the pyroelectric effect. It generates an electric charge when heated.
Boracites decompose slowly in water.
“Boracite,” Boulby Mine, Loftus, North Yorkshire, England, UK. © Rob Lavinsky, www.iRocks.com. Used with permission.
Synthetics
No known synthetics or treatments.
Sources
Cuttable crystals occur only in the Stassfurt and Hanover districts of Germany. These sites usually yield small, pale-colored crystals.
Other notable gem sources include:
- United States: Otis, California; Choctaw Salt Dome, Louisiana.
- England: North Yorkshire, Aislaby.
- Bolivia; Canada; China; France; Kazahkstan.
“Boracite” on matrix, Alto Chapare District, Chapare Province, Cochabamba Department, Bolivia. © Rob Lavinsky, www.iRocks.com. Used with permission.
Stone Sizes
Boracite crystals are very small. Usually, they yield gemstones ranging from 1-2 carats. Gems over 2 carats would be considered extreme rarities.
Care
Although boracites react to water very slowly, keep them dry in storage, where they would have time to sit and decompose. Alcohol may be used in lieu of water for cleaning. Otherwise, these stones have high hardness (7-7.5) and no cleavage and require no special care. Consult our gemstone jewelry cleaning guide for more recommendations.
“Boracite,” rare orange-pink crystal on matrix, Alto Chapare District, Chapare Province, Cochabamba Department, Bolivia. © Rob Lavinsky, www.iRocks.com. Used with permission.
