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Dolomite
Current inventory:  1 gem
 

Dolomite

Chemistry:  CaMg(CO3)2  [Calcium Magnesium Carbonate]

Discovered in 1791;   IMA status: Valid (pre-IMA; Grandfathered).
Dolomite is named after French mineralogist and geologist Deodat Guy Tancrede Gratet de Dolomieu (1750 - 1801).

 

Classification

   

   

Mineral Classification:

Carbonates

Strunz 8th Ed. ID:

5/B.03-10

 

45 : Nitrates, Carbonates & Borates
B : Waterfree carbonates without unfamiliar anions
03 : Dolomite group

 

 

Crystal Data

   

   

Crystallography:

Trigonal - Rhombohedral

Crystal Habit:

Crystals typically tabular, many minor forms, may exhibit curved faces, to 20 cm; saddle-shaped aggregates, columnar, stalactitic, granular, massive.

Twinning:

Common as simple contact twins and in combinations; also lamellar.

 

 

Physical Properties

   

 

Cleavage:

[1011] Perfect, [1011] Perfect, [1011] Perfect (rhombohedral)

Fracture:

Subconchoidal

Tenacity:

Brittle

Hardness (Mohs):

3.5 - 4.0

Density:

2.84 - 2.86 (g/cm3)

Luminescence:

May be Triboluminescent

Radioactivity:

Not Radioactive

 

 

Optical Properties

   

   

Color:

Colorless, White, Grey, Yellow, Brown, Pale Pink

Transparency:

Transparent, Translucent

Luster:

Vitreous, Pearly

Refractive Index:

1.679 - 1.703  Uniaxial ( - )  (may be anomalously Biaxial)

Birefringence:

0.1790 - 0.1810

Dispersion:

Very Strong

Pleochroism:

None

 

 

Occurances

   

   

Geological Setting:

Formed by diagenesis or hydrothermal metasomatism of limestone; a primary phase in hypersaline sedimentary environments; a major component of some contact metamorphic rocks and marbles; a gangue in hydrothermal veins; in carbonatites and ultramafic rocks.

Type Locality:

n/a

Year Discovered:

1791

View mineral photos:

Dolomite Mineral Photos and Locations

 

 

More Information

   

   

 

Mindat.org
Webmineral.com

 

 


Dolomite is a common mineral, but rarely clean enough for faceting. A rare collector's gem with distinctive birefringence. Dolomite is a common sedimentary rock-forming mineral and can be found around the world in massive beds several hundred feet thick. Crystals are somewhat rare and are usually found as druzes or clusters of small rhombohedral crystals with colorless, tan or pink colors. Large, clean, facetable crystals are quite rare. Dolomite is chemically similar to Calcite. Dolomite contains magnesium, Calcite does not.
 

  
Dolomite gems for sale:

Dolomite-001
please click on picture

Gem:

Dolomite

Stock #:

DOLO-001

Weight:

16.5165 ct

Size:

21.45 x 13.83 x 9.95 mm

Shape:

Pear

Color:

Colorless

Clarity:

Eye Clean - SI2

Origin:

Brumado, Bahia, Brazil

Treatment:

None (natural)

Price:

$315.00    [ Make an offer ]

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

Dolomite-001
please click on picture

Please click on the pictures above for a larger view.

A very large, bright and beautiful Dolomite from Brumado, Bahia, Brazil. This big gem is almost completely eye clean with a couple small, barely visible imperfections near the table.


 

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