May 12 2014
Dolomite is a carbonate mineral, consisting of calcium magnesium carbonate. It was first described as the ‘stinking stone’ by Belsazar Hacquet, an Austrian naturalist. Later, Déodat Gratet de Dolomieu, a French naturalist and geologist, described it as a rock from the Dolomite Alps in Italy.
Properties of Dolomite
The following are the key properties of Dolomite:
- Cell Data
- Space Group: R3
- a = 4.812(1)
- c = 16.020(3)
- Z = 3
- Crystal Data
- Hexagonal
- Point Group: 3
- Crystals, typical combinations of {1011} and {1120}, tabular on {0001}, many minor forms, may exhibit curved faces, to 20cm
- Saddle-shaped aggregates, columnar, stalactitic, granular, massive
- Twinning: With {0001}, {1010}, or {1120} as twin plane, common as simple contact twins and in combinations; lamellar on {0221}
- X-ray powder pattern: 2.886 (100), 2.192 (30), 1.783 (30), 1.804 (20), 2.015 (15), 1.389 (15), 2.670 (10)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| CO2 |
47.22 |
47.73 |
| CaO |
31.27 |
30.41 |
| MgO |
21.12 |
21.86 |
| FeO |
0.22 |
| SiO2 |
0.12 |
- |
| H2O |
0.02 |
- |
| Total |
99.97 |
100.00 |
- Optical Properties
- Optical Class: Uniaxial (–), anomalously biaxial
- Dispersion: Very strong
- ω = 1.679
- ε = 1.500
- 2V(meas.) = Small
- Estimated Properties
| Electron density |
Bulk density (electron density)=2.83 g/cm3
note: Specific gravity of Dolomite =2.84 g/cm3 |
| Photoelectric |
PEDolomite = 3.13 barns/electron
U= PEDolomite x ρElectron density= 8.86 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Dolomite is not radioactive
|
How to Identify Dolomite
Dolomite occurs in white, gray, reddish-white, or brownish-white forms. It has a transparent to translucent appearance. It is a non-fluorescent mineral with a vitreous lustre, a white streak and perfect cleavages.
The fractures are brittle and blocky, producing small, conchoidal fragments. Its crystals are coarse and massive. The average density of dolomite is 2.84 g/cm3, and its relative hardness ranges from 3.5 to 4.
Global Distribution
Dolomite is distributed in the following places:
- Traversella and Brosso, Piedmont, Italy
- Eugui, Navarra Province, Spain
- Trieben and Hall, Tirol, Austria
- Freiberg and Schneeberg, Saxony, Germany
- Lengenbach, Binntal, Switzerland
- Trepca, Serbia, Yugoslavia
- Frizington, Cumbria, England
- Vuoriyarvi carbonatite complex, Kola Peninsula, Russia
- Brumado, Bahia
- Morro Velho gold mine, Nova Lima, Minas Gerais, Brazil
- Naica, Chihuahua, Mexico
- Lockport, New York, USA
- Stony Point, Alexander Co. North Carolina
- Mississippi Valley region, in the Tri-State district, at Joplin
- Jasper Co. Missouri
- Galena, Cherokee Co. Kansas
- Picher, Ottawa Co. Oklahoma
Occurrence of Dolomite and Useful Mineral Association
Dolomite is formed by diagenesis, or the hydrothermal metasomatism of limestone. It occurs in a primary phase in hypersaline sedimentary environments, ultramafic rocks, and carbonatites. It also occurs as a major component of certain contact metamorphic rocks and marbles, and a gangue in hydrothermal veins.
It is closely associated with apatite, siderite, ankerite, calcite, wollastonite, forsterite, tremolite, diopside, magnetite, magnesite, serpentine, talc, quartz, gypsum, celestine, metal sulfides, barite and, fluorite.
References