The user wants to find the oxidation states of iron in the minerals haematite and magnetite.

Step 1: Determine the chemical formulas of the minerals.

• The chemical formula for haematite is $Fe_2O_3$.
• The chemical formula for magnetite is $Fe_3O_4$.

Step 2: Calculate the oxidation state of iron in haematite ($Fe_2O_3$).

1. The general oxidation state of oxygen (O) in oxides is -2.
2. Let the oxidation state of iron (Fe) be $x$.
3. Since the overall charge of the compound $Fe_2O_3$ is neutral (0), we can set up an equation: $2(x) + 3(-2) = 0$
4. Solving for $x$: $2x - 6 = 0$ $2x = 6$ $x = +3$
5. Therefore, the oxidation state of iron in haematite is +III.

Step 3: Calculate the oxidation state(s) of iron in magnetite ($Fe_3O_4$).

1. Magnetite ($Fe_3O_4$) is a mixed oxide, which means it is composed of two different oxides of the same element.
2. It can be represented as a combination of ferrous oxide ($FeO$) and ferric oxide ($Fe_2O_3$). $FeO \cdot Fe_2O_3 = Fe_{(1+2)}O_{(1+3)} = Fe_3O_4$
3. Now, we determine the oxidation state of iron in each component oxide:
   • In ferrous oxide ($FeO$): Let the oxidation state of Fe be $y$. The oxidation state of O is -2. The overall charge is 0. $y + (-2) = 0$ $y = +2$ So, one iron atom is in the +II oxidation state.
   • In ferric oxide ($Fe_2O_3$): As calculated in Step 2, the oxidation state of iron is +III. Two iron atoms are in the +III oxidation state.
4. Therefore, magnetite ($Fe_3O_4$) contains iron in two different oxidation states: +II and +III.

Step 4: Compare the findings with the given options.

• Haematite: Oxidation state is III.
• Magnetite: Oxidation states are II and III.

Let's evaluate the options:

• A: II, III in haematite and III in magnetite - Incorrect. Haematite is only III.
• B: II, III in haematite and II in magnetite - Incorrect. Haematite is only III.
• C: II in haematite and II, III in magnetite - Incorrect. Haematite is III.
• D: III in haematite and II, III in magnetite - Correct. This matches our calculated oxidation states.

Thus, the correct option is D.