Goethite
Classification:
Goethite is related to lepidocrocite and an important iron ore. Dehydration of goethitete results in haematite; compare to lepidocrocite, iron, haematite.
Synonyms/Trade Names:
None.
Chemistry/Composition:
a-FeOOH. It can contain P, V, Mn, Si, Ba, and Ca .
Structure:
The oxygen atoms are arranged in an almost hexagonal packing and surround the iron atoms octahedrally. The octahedra form chains.
Crystallographic Constants:
4.596 9.957 3.021 90.000 90.000 90.000.
Crystal Group:
Orthorhombic.
Color:
Black, brown, or yellow.
Optical Properties:
nx=2.275-2.15 ny=2.409-2.22 nz=2.415-2.23.
Pleochroism:
Brown to orange.
Powder Diagram:
4.18 2.45 2.69 1.72 (29-713).
Natural Sources:
World-wide.
Medical Importance:
Key Hazards:
Possibly fibrogenic.
Involved Organs:
Possibly lung.
Exposure/Epidemiology:
It is used as iron-ore.
Thresholds:
In Germany, MAK 6 mg/m3.
Etiology/Pathophysiology:
Detailed data are not known.
Lung Diseases:
Iron may induce a benign pneumoconiosis; for further informations see under the heading haematite.
Clinical Presentation:
Associated specific symptoms are not known.
Radiology:
Associated specific findings are not known.
Lung Function:
Usually normal findings.
Bronchoalveolar Lavage:
Usually normal findings.
Pathology:
Gross:
The lungs are of normal color and consistency.
Histology:
The alveoli can contain an increased number of macrophages, and collections of brown dust particles may be seen in the lymphatic tissue.
Prognosis:
Usually good and without serious sequelae.
Additional Diseases:
None.
Remarks:
Goethite is found in some mollusca and was identified in limpets (teeth).
References:
search Pubmed for Goethite
Fontecave M, Mansuy D, Jaouen M, Pezerat H: The stimulatory effect of asbestos on NADPH-dependent lipid peroxidation in rat liver microsomes. Biochem J 241 (1987) 561-566
Green FHY, Yoshida K, Fick G, Paul J, Hugh A, Green WF: Characterization of airborne mineral dusts associated with farming activities in rural Alberta, Canada. Int Arch Occup Environ Health 62 (1990) 423-430
Quiquampoie H: A stepwise approach to the understanding of extracellular enzyme activity in soil. Biochimie 69 (1987) 753-763