Chapter 12, Problem 12.64QP

(a)

Interpretation Introduction

Interpretation: The fraction of each type of hole occupied in ${\text{M}}_{\text{2}}{\text{SiO}}_{\text{4}}$ and the reason for larger unit cell volume of ${\text{Fe}}_{\text{2}}{\text{SiO}}_{\text{4}}$ is to be stated.

Concept introduction: The crystal structure of olivine- ${\text{M}}_{\text{2}}{\text{SiO}}_{\text{4}}$ (where $\text{M}=\text{Mg}\text{or}\text{Fe}$) is ccp arrangement with silicon in tetrahedral holes and the metal ions in octahedral holes.

To determine: The fraction of each type of hole occupied in ${\text{M}}_{\text{2}}{\text{SiO}}_{\text{4}}$.

(b)

Interpretation Introduction

To determine: The reason for larger unit cell volume of ${\text{Fe}}_{\text{2}}{\text{SiO}}_{\text{4}}$.