Among the following ores Bauxite, Siderite, Cuprite, Calamine, Haematite, Kaolinite, Malachite, Magnetite, Sphalerite, Limonite, Cryolite, the number of principal ores of iron is_______.

$\begin{array}{l}\mathrm{Bauxite} — {\mathrm{AlO}}_{\mathrm{X}}\left(\mathrm{OH}{)}_{3-2\mathrm{x}}\right(\text{ where }0<\mathrm{x}<1)\\ \mathrm{✓}\mathrm{Siderite} — {\mathrm{FeCO}}_3\\ \mathrm{Cuprite} — {\mathrm{Cu}}_2\mathrm{O}\\ \mathrm{Calamine} — {\mathrm{ZnCO}}_3\\ \mathrm{✓}\mathrm{Haematite} — {\mathrm{Fe}}_2{\mathrm{O}}_3\\ \mathrm{Kaolinite} — {\mathrm{Al}}_2(\mathrm{OH}{)}_4{\mathrm{Si}}_2{\mathrm{O}}_5\\ \mathrm{Malachite} — {\mathrm{CuCO}}_3\cdot \mathrm{Cu}(\mathrm{OH}{)}_2\\ \mathrm{✓}\mathrm{Magnetite} —{ \mathrm{Fe}}_3{\mathrm{O}}_4\\ \mathrm{Sphalerite} — \mathrm{ZnS}\\ \mathrm{✓}\mathrm{Limonite} — {\mathrm{Fe}}_2{\mathrm{O}}_3.3{\mathrm{H}}_2\mathrm{O}\\ \mathrm{Cryolite} — {\mathrm{Na}}_3{\mathrm{AlF}}_6\end{array}$