Sillimanite
Classification:
Sillimanite is the high-temperature and high-pressure modification of andalusite; compare to andalusite.
Synonyms/Trade Names:
Fibrolith.
Chemistry/Composition:
Al2SiO5 . It contains contaminations of Fe .
Structure:
The structure contains chains of octahedra, which are built by one aluminum atom and six oxygen atoms. Within these chains, the octahedra share edges with neighboring octahedra on the other side. The chains are linked by alternating silicon and aluminum tetrahedra. These tetrahedra create chains, too, and the aluminum is located half-part in a six-fold configuration and half-part in a four-fold configuration.
Crystallographic Constants:
7.440 7.590 5.750 90.000 90.000 90.000.
Crystal Group:
Orthorhombic.
Color:
Gray, brown or green color.
Optical Properties:
nx=1.657-1.660 ny=1.658-1.661 nz=1.677-1.682.
Pleochroism:
colorless to brownish.
Powder Diagram:
3.42 3.37 2.20 1.28 (38-471).
Natural Sources:
Austria, India (Khasi Hills), and Zimbabwe.
Medical Importance:
Key Hazards:
Possibly fibrogenic, possibly mutagenic.
Involved Organs:
Probably lung.
Exposure/Epidemiology:
It is used in the ceramic industries.
Thresholds:
In Germany, MAK 6 mg/m3.
Etiology/Pathophysiology:
Detailed data are not known. However, animal experiments revealed sillimanite induced lung fibrosis.
Lung Diseases:
In two porcelain workers suffering from lung fibrosis the agent sillimanit could be detected. Basically, associated specific diseases are not known; however, the mineral is listed by the ISO, i.e., possibly fibrogenic and mutagenic forms exist.
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.
References:
search Pubmed for Sillimanite
Reichel G: Auf anorganische Stäube mit geringem oder fehlendem Quarzgehalt zurückgehende Lungenveränderungen. In: WT Ulmer (Ed): Handbuch der inneren Medizin, Bd IV: Pneumokoniosen. Springer, Heidelberg (1978) 468-508
Worth G, Schiller E: Die Pneumokoniosen. Staufen, Köln (1954)