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Mineralpedia Details for Dolomite

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Dolomite

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 

Dolomite (Cobaltoan) from Bou Azzer dist., Anti-Atlas, Morocco

Dolomite (Cobaltoan)
            from Bou Azzer dist., Anti-Atlas, Morocco

Group of deep pink Dolomite rhombs to 3mm.

Deep pink crystals of Cobaltoan Dolomite.

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Dolomite (Nickeloan) from Mount Keith mine, Mt. Keith, Western Austrialia, Australia

Dolomite (Nickeloan)
            from Mount Keith mine, Mt. Keith, Western Austrialia, Australia

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.

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Dolomite from Tsumeb mine, Tsumeb, Namibia

Dolomite
            from Tsumeb mine, Tsumeb, Namibia

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.

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Dolomite from Homestake mine, Lawrence Co., South Dakota, United States

Dolomite
            from Homestake mine, Lawrence Co., South Dakota, United States

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

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Dolomite from Black Cloud mine, Leadville, Lake Co., Colorado, United States

Dolomite
            from Black Cloud mine, Leadville, Lake Co., Colorado, United States

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

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Dolomite from Queenston quarry, St. David's, Ontario, Canada

Dolomite
            from Queenston quarry, St. David's, Ontario, Canada

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

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Dolomite from Eagle mine, Gilman, Eagle Co., Colorado, United States

Dolomite
            from Eagle mine, Gilman, Eagle Co., Colorado, United States

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.

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Dolomite from Obergesteln, Wallis, Switzerland

Dolomite
            from Obergesteln, Wallis, Switzerland

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

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Dolomite from Antwerp, Jefferson Co., New York, United States

Dolomite
            from Antwerp, Jefferson Co., New York, United States
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.

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Dolomite from Morenci mine, Greenlee Co., Arizona, United States

Dolomite
            from Morenci mine, Greenlee Co., Arizona, United States

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

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