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Boracite
Current inventory:  1 gem
 

Boracite

  
Boracite's name refers to its Boron content.

Discovered in 1789;   IMA status: Valid (pre-IMA; Grandfathered)

 

Chemistry

 

 

Chemical Formula:

Mg3B7O13Cl

 

Magnesium Borate Chloride

Molecular Weight:

392.03 gm

Composition:

Magnesium

18.60 %

Mg

30.84 %

MgO

 

Boron

19.30 %

B

62.15 %

B2O3

 

Chlorine

9.04 %

Cl

9.04 %

Cl

 

-

- %

Cl

-2.04 %

-O=Cl2

 

Oxygen

53.06 %

O

 

 

 

 

100.00 %

 

100.00 %

= TOTAL OXIDE

 

 

Classification

   

   

Mineral Classification:

Borates

Strunz 8th Ed. ID:

5/L.04-10

Nickel-Strunz 10th Ed. ID:

6.GA.05

 

6 : BORATES
G : Heptaborates and other megaborates
A : Tekto-heptaborates

Related to:

Boracite Group. Boracite-Ericaite Series. The magnesium analogue of Ericaite and Chambersite. The orthorhombic dimorph of Trembathite.

Members of Group:

Boracite Group: Boracite, Chambersite, Congolite, Ericasite, Trembathite.

Varieties:

Bromboracit, Ferroan Boracite, Stassfurtite

Synonyms:

Alpha-boracite, b-Boracite, Beta-boracite, Boracite (of Werner), Borate of Magnesia, Metaboracite, Parasite

 

 

Crystal Data

   

   

Crystallography:

Orthorhombic - Pyramidal

Crystal Habit:

Euhedral crystals, to 2.5 cm, (referred to pseudotetrahedral morphology) and a dozen other modifying forms; spherulitic, plumose to fibrous, fine granular aggregates.

Twinning:

Rarely as penetration twins

 

 

Physical Properties

   

 

Cleavage:

None observed

Fracture:

Conchoidal to Irregular/Uneven

Tenacity:

Brittle

Moh's Hardness:

7.0 - 7.5

Density:

2.91 - 3.10 (g/cm3)

Luminescence:

None

Radioactivity:

Not Radioactive

Other: 

Very slowly decomposed by water. Slowly but completely soluble in HCl. Strongly piezoelectric and pyroelectric. At 265° the crystal system reverts to a high-temperature phase and the material becomes isotropic. Forms pseudomorphs after quartz (Douglashall).

Optical Properties

   

   

Color:

Pale green, greenish blue, blue, colorless, grey, white; dark green (ferroan)

Transparency:

Transparent, Translucent

Luster:

Adamantine to Vitreous

Refractive Index:

1.658 - 1.673  Biaxial ( + )

Birefringence:

0.010 - 0.011

Dispersion:

0.024 (weak)

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

Bedded sedimentary deposits of gypsum and anhydrite; salt deposits; potash deposits of the oceanic type.

Common Associations:

Anhydrite, Carnallite, Danburite, Gypsum, Halite, Hilgardite, Kainite, Magnesite

Common Impurities:

Fe(II)

Type Locality:

Kalkberg hill, Lüneburg, Lower Saxony, Germany

Year Discovered:

1789

View mineral photos:

Boracte Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Boracite is one of the rarest of collector's gems. The only facetable crystals come from the Stassfurt and Hanover districts of Germany. Boracite crystals are very small and cut gems are usually very pale blue to green or colorless. Boracite is the
magnesium analogue of Chambersite. Boracite is an evaporite mineral and is not surprisingly found with other evaporite minerals like Anhydrite, Gypsum and Halite. Boracite crystals are often embedded in these other evaporite minerals.

Locations for Boracite are in Germany, from Lüneburg, 40 km south-southeast of Hamburg, Lower Saxony; in Saxony-Anhalt, in the Stassfurt-Westeregeln-Bernburg district, at the Douglashall, Berlepsch, Solvayhall, Wilhelmshall and other mines; in Thuringia, from Bischofferode, in the Glückauf mine, Sondershausen, and elsewhere. In France, at Lunéville, Meurthe-et-Moselle. In the Boulby potash mine, northwest of Whitby, Yorkshire, England. In the Chelkar salt dome, Ak-sai Valley, Uralsk district, Kazakhstan. Large crystals from Alto Chapare, Cochabamba, Bolivia. In the USA, in the Choctaw salt dome, Iberville Parish, Louisiana, and the Louann Salt Formation, Clarke County, Alabama. From the Penobsquis and Salt Springs evaporite deposits, near Sussex, New Brunswick, Canada.
 

  
Boracite gems for sale:

Boracite-001

Gem:

Boracite

Stock #:

BORA-001

Weight:

0.1725 ct

Size:

3.50 x 3.50 x 2.34 mm

Shape:

Trilliant

Color:

Colorless

Clarity:

Eye clean

Origin:

Germany

Treatment:

None (natural)

Price:

$104.00    [ Make an offer ]

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Boracite-001

Even though this gem is small, it is relatively large for the type. A very rare gem that is eye clean and would be an interesting addition to any gem collection.


Boracite-002

Gem:

Boracite

Stock #:

BORA-002

Weight:

0.1375 ct

Size:

3.33 x 2.11 mm

Shape:

Trilliant

Color:

Colorless

Clarity:

Eye clean to VVS2

Origin:

Germany

Treatment:

None (natural)

Price:

SOLD (but we have others)

Pictures are of the actual gem offered for sale.
Gem images are magnified to show detail.

Boracite-002

A small but beautiful gem that is not often found as a round gem. A very nicely faceted Boracite.


 


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