MINERAL PROPERTIES CONTROLLING BIOLOGICAL POTENTIAL

Studies in our laboratory have shown that the physical-chemical properties of minerals control their biological potential. These properties are inherent in the nature of the material itself, are superimposed when the mineral is manipulated or processed, and are often altered following end-point application or service. We have studied and describe properties for tremolite and grunerite (as asbestiform and non-asbestiform variants).

The structures of the amphibole asbestos minerals (as a class of fibrous minerals) have been found to be defect-laden with frequent and closely spaced polysynthetic twins and chain-width errors. The anomalies result in planes along which separation may occur. Growth of unit amphibole fibrils within a fiber bundle occurs with random orientation in the ab plane. The mineral aggregate is easily dispersed on mechanical processing. The resulting fibrils are both longer and thinner than comparable manipulation of non-asbestos amphibole analogues. For asbestos, the expected amphibole cleavage is less important in producing powders. The resultant size-distributions and surface properties of amphibole asbestos and its non-asbestos analogues have been measured for grunerite (amosite) and tremolite (tremolite asbestos) and important differences are found. The differences found for asbestos and non-fibrous analogues of the same mineral are obvious on a population basis but single isolated fibers and fragments found in some environments are distinguishable only by careful electron diffraction study. Without diffraction analysis fragments of amphibole yield false positive assays for asbestos.

The biological potential of the asbestos minerals have been found to be orders of magnitude more tumorigenic than fragments of their non-asbestiform mineral analogues. Physical dimensions and surface properties for tremolite asbestos, and grunerite asbestos (amosite), explain these different behaviors.