Particular garnet structure

Finally, the particular relationship between the Cr3Si-type structure and the garnet structure (see 7.6.8) may be pointed out. The position of the cations, indeed, in the garnet structure correspond to the Cr3Si arrangement. 

Thermally activated mixed metal hydroxides, made from naturally occurring minerals, especially hydrotalcites, may contain small or trace amounts of metal impurities besides the magnesium and aluminum components, which are particularly useful for activation [946]. Mixed hydroxides of bivalent and trivalent metals with a three-dimensional spaced-lattice structure of the garnet type (Ca3Al2[OH]i2) have been described [275,1279]. 

The thermal stability of stains and oxides is particularly important in view of the high processing temperatures and therefore oxide host-lattices with spinel-, corundum-, rutile-and silicate-phases are favored as well as zircon, phenacite, garnet and sphene structures. 

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