Clay Mineralogy Exercise #4

1. Calculate the structural formula for the two samples below given the respective major elemental oxide analysis. Report your work assuming 11 oxygen equivalents per half unit cell. Show all your work.

2. Determine the tetrahedral, octahedral and interlayer layer charges for each sample.

Sample A	phengitic muscovite	Sample B	vermiculite
SiO2	46.50	SiO2	41.56
TiO2	0.15	TiO2	0.47
Al2O3	33.30	Al2O3	16.77
Fe2O3	<0.01	Fe2O3	10.48
FeO	0.20	FeO	0.90
MnO	<0.01	MnO	0.35
CaO	<0.01	CaO	4.63
MgO	3.72	MgO	23.21
K2O	9.87	K2O	0.19
Na2O	<0.01	Na2O	0.06