Whiterite

Classification:

Whiterite is a carbonate, and one of the most common Ba ores; however, it is only mined in the Great Britain.

Synonyms/Trade Names:

None.

Chemistry/Composition:

Ba(CO₃) . Sometimes with contaminations of Sr, Mg, or Ca.

Structure:

Barium atoms are placed side-to-side in layers, which create an approximately hexagonal-packed Structure, i.e., a series of layers with an identical position of atoms of layer 1 compared to that of layer 3, and an identical position of atoms of layer 2 compared to that of layer 4. These layers are packed as close as possible. The whiterit e structure is compressed along the axis, in which the layers are stacked. CO₃ groups lie between the layers; however, not exactly centered. They are rotated 30° to the right or left, and each oxygen atom has three coordinating Ba atoms.

Crystallographic Constants:

5.26 8.84 6.56 90.000 90.000 90.000.

Crystal Group:

Orthorhombic.

Color:

colorless, white, or grayish.

Optical Properties:

nx=1.529 ny=1.676 nz=1.677.

Pleochroism:

Weak.

Powder Diagram:

3.72 3.67 2.150 2.628.

Natural Sources:

Slov. Rep./Czec. Rep. (Pribram), Germany (Andreasberg), Great Britain (Alston Moore), Japan, Russia, and the USA (California, Illinois).

Medical Importance:

Key Hazards:

Possibly fibrogenic, possibly mutagenic, acute intoxication.

Involved Organs:

Lung.

Exposure/Epidemiology:

Exposure may occur in mining; the mineral is used in paper, glass and ceramic industries.

Thresholds:

In Germany, MAK 6 mg/m3.

Etiology/Pathophysiology:

Barium is absorbed through the intestines or lungs, and replaces calcium in various metabolic processes. For details, see under the heading baryte.

Lung Diseases:

Benign pneumoconiosis.

Clinical Presentation:

Symptoms include cough, expectoration, and asthmatic attacks; for details, see under the heading baryte.

Radiology:

Chest radiographs show striking nodular opacities and white patches, which will usually clear after a few months.

Lung Function:

Usually normal findings.

Bronchoalveolar Lavage:

Usually normal findings.

Pathology:

Gross:

The lungs are of normal color and consistency or display small grayish macules.

Histology:

The alveoli can contain an increased number of macrophages, and collections of brown dust particles may be seen in the lymphatic tissue. Rarely, small granulomatous lesions with monocytes and multinucleated giant cells can be seen.

Prognosis:

Usually good and without serious sequelae.

Additional Diseases:

Heart:

An increased incidence of hypertension has been reported.

Eyes:

Nonspecific conjunctivitis.

Skin:

Irritative inflammation may occur.

References:

search Pubmed for Whiterite