As it can be seen from the molecular formula of wolframite that is FeWO₄, that there is one mole of iron that is Fe in 1 mole of wolframite ( FeWO₄).
1 mole of Fe= 1 × 6.023 × 10 ²³ atoms of Fe
So there are 6.023 × 10 ²³ atoms of Fe are there in 1 moles of wolframite, FeWO₄.
So number of atoms of iron is 6.023 × 10 ²³ in 1 moles of wolframite, FeWO₄.