Arfvedsonite
Classification:
Arfvedsonite is an amphibole and belongs to the tremolite-glaukophane-riebeckite group; for further details, see under the heading amphibole , asbestos or tremolite.
Synonyms/Trade Names:
Asbestos.
Chemistry/Composition:
Na3(Fe2+,Mg,Fe3+,Al)4(Al(OH/Si4O11)2 . The composition of this mineral is only rarely fully identical to the formula: usually additional contents of Ca and Al are found .
Structure:
The silicon and aluminum atoms containing oxygen tetrahedra are linked and form chains. Two of these chains are bonded, respectively, and form a double chain, which is built by rings of six-membered tetrahedra. Two tetrahedra belong to the two neighboring rings, respectively, and only two of them to the ring itself. The chains can be described by the chemical formula (Si4O11)n. The separated chains are bonded by cations and partially by hydroxyl ions.
Crystallographic Constants:
9.900 18.000 5.300 90.000 104.000 90.000.
Crystal Group:
Monoclinic.
Color:
Normally greenish black, black or yellowish green.
Optical Properties:
nx=1.633-1.702 ny=1.639-1.705 nz=1.642-1.707.
Pleochroism:
Bluish green to bluish gray.
Powder Diagram:
3.16 2.73 8.51 3.42 (14-633).
Natural Sources:
Mined in Italy, Norway (Langesundfjord), and Russia (Rayon Mariopul).
Medical Importance:
Key Hazards:
Fibrogenic, carcinogenic.
Involved Organs:
Lung, peritoneum, skin, kidneys.
Exposure/Epidemiology:
The amphibole minerals are of great technical interest. Their fibrous form is related to their specific physical properties such as heat resistance, electrical insulation, etc. Important sources of exposure are shipyards, manufacture of fire-resistant textiles, sheets, automobile brakes, filters for various fluids, etc. For details, see under the heading asbestos .
Thresholds:
See under the heading asbestos .
Etiology/Pathophysiology:
The inhaled fibers activate complement-derived chemotactic activity on alveolar surfaces, pneumocytes, macrophages, and mesothelial cells. Immunologic compartments such as interleukins and tumor necrosis factor are probably involved. For details, see under the heading asbestos .
Lung Diseases:
All amphiboles can crystallize in fibrous varieties, and can induce interstitial lung fibrosis, pleural diseases such as fibrosis, pleural plaques, benign and malignant tumors of the lung, pleura, peritoneum, gastrointestinal tract, lymphatic system, kidneys. For details, see under the heading asbestos .
Clinical Presentation:
Chronic cough and shortness of breath during physical exercise are usually the first symptoms; chest pain is often associated with pleural tumors.
Radiology:
Chest radiographs are often normal in patients with early changes. Others may display diffuse interstitial densities, pleural thickening or effusion.
Lung Function:
Progressive restrictive changes or severe obstructive alterations are seen.
Bronchoalveolar Lavage:
The inhaled mineral fibers can be analyzed and quantified in the lavage fluid. Increased levels of complement C5 or altered ratio of the T4/T8 lymphocytes correspond with the activity of the fibrotic lesions.
Pathology:
Gross:
The lungs may display an increased consistency, a thickened and fibrotic pleura, honeycombing, or circumscribed white-yellowish tumor masses. For details, see under the heading asbestos .
Histology:
The fibers are birefringent and often coated with iron-protein mucopolysaccharide substances (asbestos bodies). They are usually deposited in the distant airways and can be ingested by macrophages. Diffuse interstitial fibrosis associated with scattered mononuclear inflammatory infiltrates and acellular collagenous fibers in the pleura are common findings. Benign and malignant tumors of various cell types (most frequently common lung carcinoma and mesothelioma) can develop. For details, see under the heading asbestos .
Prognosis:
Usually poor due to serious sequelae.
Additional Diseases:
See under the heading asbestos .
References:
search Pubmed for Arfvedsonite
Pylev LN, Iankova GD: Carcinogenic activity of magnesia arfvedsonite (group of amphibole asbestos minerals) administered intrapleurally to nonbred rats. Vopr Onkol 21 (1975) 71-76