Polymorf - Knowhwere- Topological classificaton of minerals

Topological mineral table

The following table classifies minerals topologically by the type and percent

occupation of the interstitial voids present in the atomic packing. It gives the type of

void, percent occupation rate, structure type, packing arrangement, general formula,

and coordination of the interstitial A atoms and the close packed X atoms. More

detailed treatments of these parameters describing each particular structure can be

found in the sections following the table. They are organized in the order of the

table which can be followed by clicking on the directional arrows at the bottom of

each page. Clicking on the name of the structure will also open up its description

directly.

.
Void	%	Structure	Packing	Formula	Coordination^*

Tetrahedral	100	antifluorite	fcc	A₂X	A- 4c, X- 8c
	50	zincblende	fcc	AX	A- 4c, X- 4c
	"	litharge	fcc	AX	A- 4c, X- 4c
	"	wurtzite	hcp	AX	A- 4c, X- 4c
	25	HgI₂	fcc	AX₂	A- 4c, X- 2c
	1/6	Al₂Br₆	hcp	A₂X₆	A- 4c
	1/8	SnI₄	fcc	AX₄	A- 4c
Octahedral	100	halite	fcc	AX	A- 6c, X- 6c
	"	NiAs	hcp	AX	A- 6c, X- 6c
	2/3	corundum	hcp	A₂X₃	A- 6c, X- 4c
	50	CdCl₂	fcc	AX₂	A- 6c, X- 3c
	"	boehmite	fcc	AOX	A- 6c; X- 4c,3c,2c
	"	atacamite	fcc		A- 6c; X- 3c, 4c
	"	CdI₂	hcp	AX₂	A- 6c, X- 3c
	"	rutile	hcp	AX₂	A- 6c, X- 3c
	"	diaspore	hcp	AO(OH)	A- 6c; O- 3c, OH- 3c
	3/8	Nb₃Cl₈	fcc	Nb₃X₈	A- 6c; X- 2c, 3c
	1/3	bayerite	hcp	AX₃	A- 6c, X- 2c
	"	gibbsite	ABBAA		A- 6c, X- 2c
	"	YCl₃	fcc	AX₃	A- 6c, X- 2c
	"	RhF₃	fcc	AX₃	A- 6c, X- 2c
	"	ZrI₃	hcp	AX₃	A- 6c, X- 2c
	25	perovskite	fcc	ABO₃	A- 6c, X- 2c
	"	ReO₃	fcc	AX₃	A- 6c, X- 2c
	20	Mo₂Cl₁₀	fcc	A₂X₁₀	A- 6c, X- 2c
Tetra/Octa	100	Cu₂AlMn	fcc		Al- 6c, Cu- 4c, Mn- 6c
	1/8,1/2	spinel	fcc	ABO₄	A- 4c, B- 6c, X- 4c
	1/8,1/2	olivine	hcp	A₂SiO₄	A- 6c, Si- 4c
Cubic	100	CsCl	cp	AX	A- 8c, X- 8c
	50	fluorite	cp	AX₂	A- 8c, X- 4c
Trigonal prism	100	AlB₂	hp	AX₂	A- 6c, X- 12c
	50	molybdenite	hp	AX₂	A- 6c, X- 3c

* coordination numbers are A atoms in relation to X atoms and vice versa

Table 5 - Classification of minerals in terms of their occupied interstitial voids

This table shows that varying the type and percent occupation of interstitial voids

changes the coordination of the constituent atoms of a substance and therefore the

geometry and symmetry of the resulting atomic structure. It gives a concrete,

physical, and straightforward explanation of why substances look and act the way

they do. The following section illustrates in graphic detail how this dynamic

interplay between form and function affects the physical and chemical properties

of the mineral structures listed above.

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