Name the following minerals: (a) $\mathrm{MgCO}_3$, (b) $\mathrm{Na}_3 \mathrm{AlF}_6$, (c) $\mathrm{Al}_2 \mathrm{O}_3$, (d) $\mathrm{Ag}_2 \mathrm{~S}$, (e) HgS, (f) ZnS , (g) $\mathrm{SrSO}_4$, (h) $\mathrm{PbCO}_3$, (i) $\mathrm{MnO}_2$, (j) $\mathrm{TiO}_2$.