Question

The mineral that contains both magnesium and calcium is:

• A. Magnesite
• B. Calcite
• C. Carnallite
• D. Dolomite

Hint:

Look for the mineral whose formula has both Ca and Mg together.

Answer 1

The Correct Option is D

Check each mineral's formula one by one against the requirement of containing both metals.

1. Requirement: the mineral must have magnesium and calcium both present.
2. Magnesite, $MgCO_3$: only magnesium, no calcium. Rejected.
3. Calcite, $CaCO_3$: only calcium, no magnesium. Rejected.
4. Carnallite, $KCl \cdot MgCl_2 \cdot 6H_2O$: has magnesium and potassium, but no calcium. Rejected.
5. Dolomite, $CaMg(CO_3)_2$: has both calcium and magnesium in one formula. This fits.
6. So the answer is option D, Dolomite.