Asbestos minerals

ALCOHOLS,HIGHERALIPHATIC-SURVEY AND NATURALALCOHOLSMANUFACTURE] (Vol 4) -in asbestos minerals [ASBESTOS] (Vol 3)... 

R. G. Bryans and B. Lincoln, Paper 6.24, 3rd International Conference on the Physics and Chemistry of Asbestos Minerals, Qunbec, Canada, 1975. 

A. A. Hodgson and C. A. White, Papers 2—10, The Physics and Chemistry of Asbestos Minerals, Ouford Conference on Asbestos Minerals, Oxford, UK, 1967. 

Serpentine An asbestos mineral with a wav-y appearance, such as chrysotile. 

Many properties of silicates can be understood in terms of the type of network lattice formed. In the one-dimensional networks, shown in Figure 17-8, the atoms within a given chain are strongly linked by covalent bonds but the chains interact with each other through much weaker forces. This is consistent with the thread-like properties of many of these silicates. The asbestos minerals are of this type. 

Even more complicated chemical formulas result when some silicon atoms have one outer oxygen atom, whereas others in the same mineral have two outer oxygen atoms. The asbestos minerals—one is crocidolite,... 

Wet milling, asbestos minerals, 3 308 Wet permanent setting in wool processing, 26 388 Wet phosphoric acid, economic aspects of, 18 860... 

The most common, and certainly the most familiar, inorganic fibers are the mineral fibers known as asbestos. Several minerals have been mined as asbestos (Fig. 1.1 A, C see chapter 2 for a detailed discussion of the asbestos minerals). These minerals are widespread in nature, but mining is economical only when they occur as continuous fibrous aggregates (veins) crosscutting rock masses. The veins are made up of hairlike fibers in parallel array that, on close inspection, appear bent (Fig. I.IB). Not surprisingly, a mineralogical term, asbestiform, has been used to describe this subset of inorganic materials. 

The data in the references provided for each entry in the Appendices are extremely variable. Except for those of the asbestos minerals, the general descriptions of most minerals give little more than cursory mention of their occurrence as fibers. A journal citation indicates some information on composition, crystal structure, size, morphological characteristics, and other... 

Table 2.4 lists the major amphibole mineral series and illustrates the chemical range of the group. The five commercial asbestos varieties are starred. Idealized chemical formulas for the amphibole asbestos minerals are as follows ... 

Over the past several decades six different silicate minerals have been mined as asbestos and processed for industrial and commercial applications. The most commonly encountered asbestos mineral today is chrysotile. The five other minerals are tremolite, actinolite, anthophyllite, grunerite, and rie-beckite. All five are members of the amphibole group of minerals, and each can occur as chunky, acicular, or equant crystals, as well as in fibrous form. When found as fine fibrous aggregates, in quantities appropriate for mining, they are usually distinguished as a special variety—for example, tremolite-asbestos. 

Two to 3 percent of the world s total asbestos production has been of the crocidolite variety, most of which has come from South Africa. Western Australia was a minor producer of crocidolite between 1944 and 1966. All amosite has been mined in the Transvaal Province of South Africa (2 to 3 percent of the world total). The only significant anthophyllite production came from Finland, where about 350,000 tons were mined between 1918 and 1966. Table 2.6 lists the composition, optical, and diffraction characteristics of the six asbestos minerals. More information on individual mineral species can be found in the references accompanying the sections on serpentine and amphibole types. Discussion of the geology, terminology, and exploitation of the several types of asbestos can be found in Ross (1981). 

Table 2.6 Comparison of the Diffraction, Optical and Mechanical Properties of the Six Asbestos Minerals... 

Because of the international sources of asbestos minerals, the variety of manufacture and use of asbestos and asbestos products, notably as insulation and in cement pipe, coupled with the publicity given to their potential health effects, there is probably not a single country in the world that has not become attuned, in the last ten years, to the hazards of asbestos exposure. The epidemiological data collected on disease related to asbestos exposure, es-... 

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