Crystal structures diopside

Diol complexes, 9 211 d ion complexes, heavier, structure changes prior to ligand exchange, 34 258-259 Diopside, 4 61 crystal structure of, 4 51 p-Dioxane complexes, osmium, 37 312... 

Fig. 9, from Warren s 1929 paper on the crystal structure and chemical composition of amphiboles 48>, is a physical picture of the silicon-oxygen chain in diopside. Large circles represent van der Waals-like domains of oxide ions (r = 1.40 A 2>) smaller, dashed circles represent van der Waals-like domains of silicon cations [r = 0.41 A 2>). 

Wilkins and Sabine (1973) used IR spectroscopy to determine water contents of kyanite, andalusite, sillimanite, grossular, andradite, pyrope, diopside, olivine, and feldspars. They found low water contents 0.008 wt.% in olivine, 0.02 wt.% in diopside, and 0.009 wt.% in pyrope. Zemann, Beran, and co-workers published a series of papers on IR spectroscopy of both hydrous minerals and NAMs (e.g., Tillmanns and Zemann, 1965 Beran and Zemann, 1971, 1986 Beran, 1971, 1986, 1987 Beran and Gotzinger, 1987 Beran et al., 1993). For the most part, these contributions were focused on the substitutional mechanisms by which hydrogen entered the crystal structure, rather than on the absolute amount of hydrogen in the crystal structure. 

As a further example of a structure building exercise, consider the mineral diopside, CaMg-Si206, which was one of the first crystal structures to be determined, during the early years of X-ray crystallography. The crystallographic data is given in Table 5.12. 

Proof that the anions of the substances mentioned really consist of long chains of P04 tetrahedra has been supplied by complete structural analyses of crystals. Four different types of such chain-like anions, differing in shape and inner periodicity, have so far been recognized. In the low temperature form of lithium polyphosphate, which has the same type of structure as lithium polyarsenate and diopside [Ca, Mg(Si03)2]x these are extended chains which (see Fig. 9a) as in enstatite have a Zweierperiodizit at (138) (see also ref. 66 in Table XVI). Rubidium polyphosphate has quite similar Zweierketten (55) (see Fig. 9b and ref. 63 in Table XVI) except that the P04 tetrahedra are somewhat rotated with respect to Form a. In the high... 

Kirby, S. H., Christie, J. M. (1977). Mechanical twinning in diopside Ca(Mg, Fe)Si206 structural mechanism and associated crystal defects. Phys. Chem. Minerals, 1, 137-63. 

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