Question

Answer for each of the following cubic minerals:

MnS (Albandite), As₂O₃ (Arsenolite), and FeCr₂O₄ (Chromite)

a) Suggest a possible arrangment of the atoms (or ions) in a cubic unit cell. Which group or atom apperars where in the cubic cell? (edge, center, face, or corenr points)

b) Identify the type of cubic unit cell as SC, BCC, or FCC.

Answer 1

a)
MnS : Sulfide ions are at corner and the center of each face, Mn ions are around them i.e at the center
of each edge.
As₂O₃ : O^2- at corner all corners and center of each face, As⁺³ are around them
FeCr₂O₄ : Cr₂O₄^- units at center of faces and at corners , Fe⁺ ions are at center of each edge

b) All the three have FCC structure.