Polymorf - Knowhwere- Octahedral summary

Summary of minerals with AX₆ coordination group structures

Here again the packing arrangement of the close packed X atoms and the percent

occupation of the interstitial voids determined the number and types of linkage

surfaces of the AX₆ coordination groups of minerals and their chemical composition.

The number of octahedral interstices in a crystal structure is equal to the number of

close packed atoms. Hence the chemical formula for structures with a given percent

occupation rate of their octahedral voids can be deduced a priori.

.
	%occupation	formula
	100	AX
	2/3 (66.7%)	A₂X₃
	50	AX₂
	1/3 (33.3%)	AX₃
.
Table 7 - Percent occupancy versus formula for AX₆ mineral structures

The following section also establishes the structural basis for the chemical

composition of minerals with interstitial atoms occupying both octahedral and

tetrahedral voids, as well as cubic and trigonal prismatic interstices.

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