Click on a letter above to view the list of gems.  

Dolomite
Current inventory:  1 gem
 

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: