Dolomite Value, Price, and Jewelry Information


DOLOMITE: Spain (4.5). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Dolomite is a rarely seen gem with distinctive Birefringence (as a carbonate) but is too soft and fragile for wear Spanish crystals are widely sold to collectors so transparent material is fairly abundant.

Dolomite Value

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Dolomite Information

DataValue
NameDolomite
Crystallography Hexagonal (R). Crystals rhomb shaped, sometimes with curved faces; saddle-shaped; massive or granular; twinning common.
Colors Colorless, white, gray, green, pale brown, pink (Mn present). Ankerite is tan to brown, and kutnahorite is pink. Dolomite may also be pink due to Co.
Luster Vitreous to pearly.
Fracture Subconchoidal. Brittle.
Hardness 3.5-4: varies with direction in crystal.
Specific Gravity 2.85, as high as 2.93; ankerite, 2.93-3.10.
Birefringence 0.179-0.185. (Ankerite, 0.182-0.202).
Cleavage Perfect 1 direction.
Stone SizesMassive material is generally carved; often it is stained pretty colors and may be naturally color banded. Faceted dolomite from New Mexico reaches a size of about 5 carats. Spanish material can provide stones over 100 carats. Private Collection: 18.38 (Spain).
Luminescence Orange, blue, pale green, creamy white, weak brown in SW. Orange, blue, pale green, creamy white in LW.
Spectral Not diagnostic.
FormulaCaMg(CO3)2 + Fe, Mn, Zu, Pb, Co. Note: CaFe(CO3)2 = Ankerite. CaMn(CO3)2= Kutnahorite. There is a complete series from dolomite, through ferroan dolomite, to ankerite.

Optics:

dolomite: o = 1.679-1.703; e= 1.500-1.520. Uniaxial (-).

ankerite: o = 1.690-1.750; e = 1.510-1.548. Uniaxial (-).

Indices increase from dolomite values with increasing substitution of iron.

Occurrence: In sedimentary rocks; in Mg-rich igneous rocks that have been altered; geodes.

Quebec, Cananda; Mexico; Brazil; Germany; Austria; Switzerland.

Missouri, Oklahoma, Kansas: so-called Tri-State Mineral Region.

Keokuk, Iowa: in geodes.

New Mexico: transparent material, cuttable.

Lingua, Navarra, Spain: magnificent crystals and clusters, often large size, perfectly formed and completely transparent.

Pribram, Czechoslovakia: cobaltian dolomite (pink).

Czechoslovakia and Hungary: kutnahorite.

Ankerite is a mineral of veins and hydrothermal or lowtemperature deposits.

Comments: Dolomite is a rarely seen gem with distinctive Birefringence (as a carbonate) but is too soft and fragile for wear Spanish crystals are widely sold to collectors so transparent material is fairly abundant.

Name: After Deodat Dolomieu, French engineer and mineralogist.