A range of other nonasbestos minerals can display a tubular morphology, including halloysite, palygorskite, talc, and vermiculite, and although their tubular forms are rare, their absence can only be proved using quantitative SAED or EDX. These observations and measurements can be made directly from the screen if the appropriate calibrated screen markings are available, but records should be made of a certain number of fibers in any sample. Chrysotile fibrils, with their cylindrical form, will usually give the same characteristic pattern, corresponding to a 0.73 nm spacing for (0 0 2) planes, and a layer line repeat of 0.53 nm, as well as streaking of the (1 1 0) and (1 3 0) reflections. Such a pattern indicates that the material is crystalline. Qualitative SAED consists of observation of the pattern of diffraction spots obtained on the TEM viewing screen from a randomly oriented fiber or particle. Wrona, in Encyclopedia of Analytical Science (Third Edition), 2019 TEM ED
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