Mineralpedia Details for Dolomite

Dieudonne Sylvain Guy Tancrede de Gratet de Dolomieu is the namesake of Dolomite, a French geologist and naturalist who was a contributor to the earliest descriptions of the species found in dolostone. Dolomite is a common and major rock forming mineral and is abundant and widespread worldwide. A few localities noted for fine material include in Italy, Spain, Austria, Germany, Switzerland, Kosovo, England, Russia, Brazil, Mexico, and the United States. The origin of dolomite is still somewhat uncertain, but it believed to form via diagenesis or by hydrothermal metasomatisim of limestone. It is a primary phase in hypersaline sedimentary environments, is a major constituent of contact metamorphic rock and marbles in some cases, can be found as a gangue mineral in hydrothermal veins and can be found in carbonatites and ultramafic rocks. Dolomite can fluoresce white to pink under ultraviolet light and is triboluminescent.

Ref. Handbook of Mineralogy, Anthony et al (1995) and MSA at http://www.handbookofmineralogy.org/pdfs/dolomite.pdf

Formula

CaMg(CO₃)₂ 

Crystal System

Trigonal 

Crystal Habit

Crystalline - Coarse, Massive, Blocky - Rhombohedral 

Cleavage

Perfect, Perfect, Perfect 

Luster

Vitreous (Glassy) 

Color

white, gray, reddish white, brownish white, gray 

Streak

white 

Class

Trigonal - Rhombohedral 

Fracture

Brittle - Conchoidal 

Hardness

3.5-4 

WebMineral

View Dolomite 

Mindat

View Dolomite 

Group of deep pink Dolomite rhombs to 3mm.

Deep pink crystals of Cobaltoan Dolomite.

Dolomite with a light lime green to yellow, an unusual color caused by a high Nickel content. The crystals covering the face are rosettes to 7mm and totally cover the matrix.

Large curved saddle-like crystals of Dolomite to 2cm with a nice golden-yellow sheen.

White curved rhombic crystals to 1cm.

Pink crystalline mass of Dolomite colored pink by cobalt. Dolomite formed an important constituent of the gangue rock at Tsumeb.  Other than some primary sulfides (linnaeite, glaucodot, carrollite), which are very rare, there are no important cobalt minerals at Tsumeb.

Pink rhombic crystals mostly to 3mm but also having larger 7mm crystals perched at the top.

White rhombic crystals to 5mm. Excellent clean specimen from this famous mine.

Creamy white crystal clusters to 1.5cm on Galena matrix with Sphalerite and Quartz.

Soft pink Dolomite rhombic crystals to 1 plus cm in large vug.

Creamy tan large Dolomite rhombic crystals to 1.2cm across. 

Sharp creamy rhombic Dolomite crystals from 6 to 11mm on edge. One the crystals, as seen in the last photo, has a small black Sphalerite crystal at the center of a seemingly incomplete crystal of Dolomite.

Creamy white, lustrous rhombic crystals in curved habit to 1cm.

Special Info

ex. Charles Noll

This specimen has a large pocket lined with platy Hematite and water clear Quartz. The large white balls are aggregates of Dolomite to 1cm. Mineralogically, a simple specimen but naturally perfect with good contrast of white on black. Very hard to get any specimens from this long classic locality.

White Dolomite rhombs with a slight pink color to 4mm.