Table of Contents
Dolomite Mineral and a Rock Dolomite Mineral and a Rock Dolomite Lumps, Packaging Type Loose Dolomite – Large specimen with thick tabular white, glossy crystals to 2cm. . This and many more mineral specimens are available for sale at Dakota Matrix Minerals. Dolomite – After I got to looking at this specimen, I realized how nice it actually is. The crystals of Dolomite are large and prestine. The largest crystal is 2cm wide. All about matrix…
Dolomite is an important rock-forming mineral that named is French mineralogist Déodat Gratet de Dolomieu. It is a colorless to white, pale brown, grayish, reddish, or pink mineral. Its crystals are commonly rhombohedral or tabular, often have curved faces, and sometimes cluster in saddle-shaped aggregates. Dolomite may be striated horizontally and twinned. Some crystals may be up to 2 in (5 cm) long. It can also be coarse to fine granular, massive, and, rarely, fibrous.
Polymorphism & Series: Forms two series, with ankerite and with kutnohorite.
Mineral Group: Dolomite group.
Name: Honors Dieudonne (D´eodat) Sylvain Guy Tancr`ede de Gratet de Dolomieu (1750–1801), French geologist and naturalist, who contributed to early descriptions of the species in dolostone.
Association: Fluorite, barite, calcite, siderite, quartz, metal sulfides (hydrothermal); calcite, celestine, gypsum, quartz (sedimentary); talc, serpentine, magnesite, calcite, magnetite, diopside, tremolite, forsterite, wollastonite (metamorphic); calcite, ankerite, siderite, apatite (carbonatites).
Formation
Dolomite is the main constituent in dolomite rocks and dolomitic marbles. It occurs as a replacement deposit in limestone affected by magnesium-bearing solutions, in talc schists, and in other magnesium-rich metamorphic rocks. Dolomite is found in hydrothermal veins associated with lead, zinc, and copper ores. It is also found in altered, silica-poor igneous rocks, in some carbonatites, and in serpentinites. Crystals of dolomite frequently form in cavities in limestone and marble.
Chemical Properties of Dolomite
Chemical Classification | Carbonate |
Chemical Composition | CaMg(CO3)2 |
Common Impurities | Fe,Mn,Co,Pb,Zn |
Physical Properties of Dolomite
Color | Colorless, white, pink, green, gray, brown, black |
Streak | White |
Luster | Vitreous, pearly |
Cleavage | Perfect, rhombohedral, three directions |
Diaphaneity | Transparent to translucent |
Mohs Hardness | 3.5 to 4 |
Crystal System | Hexagonal |
Tenacity | Brittle |
Density | 2.84 – 2.86 g/cm3 (Measured) 2.876 g/cm3 (Calculated) |
Parting | Noted in lamellar twins on {0221}. Twin gliding on {0221}; |
Optical Properties of Dolomite
Dolomite PPL Dolomite XPL
RI values: | nω = 1.679 – 1.681 nε = 1.500 – 1.503 |
Twinning | Common as simple contact twins |
Optic Sign | Uniaxial (-) |
Birefringence | 0.179 |
Relief | Moderate |
Optical Extinction | Parallel |
Occurrence
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.
Uses Area
- Construction aggregate
- Cement manufacture
- Dimension stone,
- Calcined to produce lime,
- Sometimes an oil and gas reservoir,
- A source of magnesia for the chemical industry, agricultural soil treatments,
- Metallurgical flux
Distribution
A major rock-forming mineral, abundant worldwide with numerous commercial uses. Some localities for fine examples include:
- In Italy, from Traversella and Brosso, Piedmont.
- Exceptional crystals from Eugui, Navarra Province, Spain.
- At Trieben and Hall, Tirol, Austria. From Freiberg and Schneeberg, Saxony, Germany.
- At Lengenbach, Binntal, Switzerland. From Trepca, Serbia, Yugoslavia. At Frizington, Cumbria, England.
- In the Vuoriyarvi carbonatite complex, Kola Peninsula, Russia.
- Fine crystals from Brumado, Bahia, and in the Morro Velho gold mine, Nova Lima, Minas Gerais, Brazil.
- At Naica, Chihuahua, Mexico.
- In the USA, in New York, from Lockport, Niagara Co., eastward to Walworth, Wayne Co.; at Stony Point, Alexander Co., North Carolina; in the Mississippi Valley region, in the Tri-State district, at Joplin, Jasper Co., Missouri; Galena, Cherokee Co., Kansas; and Picher, Ottawa Co., Oklahoma.
References
- Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.
- Handbookofmineralogy.org. (2019). Handbook of Mineralogy. [online] Available at: http://www.handbookofmineralogy.org [Accessed 4 Mar. 2019].
- Mindat.org. (2019). Orpiment: Mineral information, data and localities.. [online] Available at: https://www.mindat.org/ [Accessed. 2019].
- Smith.edu. (2019). Geosciences | Smith College. [online] Available at: https://www.smith.edu/academics/geosciences [Accessed 15 Mar. 2019].