Комиссия IMA по новым минералам и названиям минералов: нормы и рекомендации по номенклатуре минералов, 1998 Вопрос размераThe matter of size
The main criteria for defining a mineral species are its composition and crystal structure; with the development of modern analytical techniques, it is now possible to perform complete chemical and crystal-structure analyses on nanometric volumes, i.e., on the scale of a few Ångström units. Should such submicroscopic domains be accepted as valid mineral species? There is a wide range of opinions on this subject. On the one hand, it is argued that if a mineral substance can be characterized in terms of composition and crystallography, then it should be regarded as a valid mineral species. On the other hand, it is contended that the other properties traditionally reported for minerals, such as color, hardness, optical properties, etc., cannot be determined on an area of that size, and that the description is therefore incomplete.
Furthermore, the size of the described particle should be sufficiently large so that sufficient type material can be retained to enable a later independent examination to confirm the original characterization. Another argument against the acceptance of nanometric specimens as valid mineral species is that such substances cannot be adequately displayed in mineral museums. It has not been possible to reach agreement on a minimal acceptable size for a mineral substance to
be regarded as a species, and therefore each case must be decided on its own merits.
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