The structure of denisovite, a fibrous nanocrystalline polytypic disordered `very complex' silicate, studied by a synergistic multi-disciplinary approach employing methods of electron crystallography and X-ray powder diffraction

What is it about?

...one of the most complex mineral structures solved after more than 30 years... Denisovite has been described and officially approved as a new mineral species already in 1984. However, its chemical formula, symmetry and structure have remained incompletely known ever since, because of the high complexity of the mineral. Some of the reasons for this long-standing knowledge gap are addressed in the title of the publication. The gap has now been closed by using a wide range of methods, including microprobe analysis, model building, various methods of electron crystallography - imaging as well as diffraction -, and X-ray powder diffraction. The results were analysed and interpreted using topological analysis, symmetry considerations and OD theory. In view of the interdisciplinary character of IUCrJ and its diverse readership, the authors took great care in making the paper readable even for non-specialists. Some of the intricacies of complex minerals and the interrelationships and complementary of the methods employed are explained and discussed.

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Why is it important?

Denisovite is not of special importance beyond the realm of mineralogy. However, the importance of the present work relies on the fact that denisovite can be considered as a representative of many natural and synthetic phases formed under near ambient conditions where lithosphere, hydrosphere, atmosphere and even bioshere meet and where our human lifes happen. Many of the phases formed under such conditions present similar difficulties in determining their structures and properties as denisovite. The example of denisovite demonstrates strikingly that for such complex cases multi-disciplinary approaches are not only useful, but indispensable.