Identification and quantitation of microparticles in solid materials

Variation in the precise conditions of geological formation may produce variations in the exact composition of asbestos minerals of a particular class, and thus in their biological interactions. Examples are given of differences in O18/O16 ratios, TiO2 content, lattice substitutions, substitution of Al (III) for Si (IV) and attachments to spare hydrostatic charges.

Identification and Quantitation of Microparticles in Solid Materials by D. R. Bowes* Variation in the precise conditions of geological formation may produce variations in the exact composition of asbestos minerals of a particular class, and thus in their biological interactions. Examples are given of differences in 018/016 ratios, TiO2 content, lattice substitutions, substitution of Al (III) for Si (IV) and attachments to spare hydrostatic charges.
Some the geological, geochemical, and mineralogical factors to be considered in attempts to "type" asbestos minerals for comparison with mineral particles extracted from biological tissue for identification and quantitation by electron microscopy and other techniques are summarized.
The crustal situation of many economically exploited asbestos bodies is in mobile belts associated with major oceanic-continental plate boundaries, for example the Appalachian belt. In this situation, ultrabasic masses are emplaced, and hydrothermal solution activity and metasomatism commonly accompanies metamorphism and deformation, one result being the development of chrysotile from the ultrabasic rocks. As the proportions of water derived from sediments, igneous intrusions and meteoric sources may vary, so the proportions of 016 and 018 may also vary both from one asbestos body to another and within a single body.
Similar looking amphibole-rich rocks (amphibolites and hornblende schists) may show significant differences in major and trace element chemistry indicative of derivation by metamorphism of either igneous or sedimentary rocks, as in the case of bedrock of New York City (Fig. 1). Here, differences in TiO2 proportions (by a factor of 12) and in the proportions of other constituents portend differences in surface properties and response to biological fluids of amphiboles inhaled and ingested by tunnel construction workers. Many amphibole-bearing rocks show evidence of more than one phase of amphibole growth.
Differences in temperature and pressure conditions are reflected by varying chemistry due to lattice substitutions and often by shape characteristics such as length/breadth ratio.

December 1974
Amphiboles show a very wide range of compositions, resulting from lattice substitution. A general formula is X2-3Y5Z8022(OH,F)2, where X is commonly Ca, Na, or Mn; Y is commonly Mg, Fe, Ti, Al, or Mn; Z is mainly Si, but replaceable up to about 25% by trivalent ions with a radius up to 0.67 A, particularly Al.
The amphibole structure is based on a Si401O double chain unit (Fig. 2). Two Si401 double chain units sandwich the Y ions (Mi, M2, and M3 in Fig. 3) between them. The X ions, up to two in number, occupy the M4 position; any in excess of two occupy the A position. The extent of substitution in the X and Y sites is shown by the compositions of two amphibole asbestos minerals (  Substitution of Al (III) for Si (IV) in the Si4011 double chain unit is electrostatically balanced by Na +1 going into the A position. In addition the Si Al substitution only occurs in certain of the Si sites which parallel the (110) cleavage plane (Figs. 2, 3). In this way the size of cleavage fragments, their length/breadth ratio and their surface properties may be changed.
In summation, variations in shape, size, surface properties, and chemical composition of amphibole asbestos minerals provide body fluids with a multichoice situation.
The final point is possibly esoteric, but possibly very practical. Silicate minerals have Environmental Health Perspectives regular and repeated Si=O units with substitutions of linking cations and a pattern of the substitution of Si (IV) by Al (III) in the basic unit. In the case of at least some silicates (clays), organic molecules (alcohols) adhere to their surfaces by utilizing spare hydrostatic charges. Is it possible, then, that minerals such as clays, asbestos minerals, talc, and micas act as templates for the initial message carriers (4), i.e., are silicate minerals with sheet and chain lattice structures the precursors of a genetic code?