All the candidates attempted this questions and they performed very well. The question requested the candidates to give the following points:
Classes of minerals

1. Metallic minerals e.g. haematite, magnetite, galena, sphalerite, gold, tantalite, cassiterite
2. Industrial minerals or non-metallic minerals e.g. limestone, marble, gypsum, feldspar,  baryte
3. Construction minerals e.g. granite, sand, gravel, conglomerate
4. Energy minerals e.g. coal, uranium, tar sand, petroleum

OR
The major classes of minerals based on chemical composition are:

1. native elements: e.g. gold, silver, graphite,
2. sulphides: PbS, ZnS
3. sulfosalts,
4. oxides: Fe3O4, Fe2O3, SnO2
5. hydroxides,
6. halides,
7. carbonates, CaCO3
8. nitrates,
9. borates,
10. sulfates,
11. phosphates, and
12. silicates.