On the Mohs hardness scale used in mineral processing, which of the following is the softest material?

Introduction / Context:
The Mohs scale ranks minerals by scratch resistance from 1 (softest) to 10 (hardest). Knowledge of hardness guides equipment selection and wear considerations in comminution.

Concept / Approach:
On the Mohs scale: Talc = 1, Gypsum = 2, Calcite = 3, Feldspar ≈ 6, Corundum = 9. Therefore, talc is the softest listed mineral.

Why Other Options Are Wrong:
Calcite: hardness 3.Feldspar: hardness ~6.Corundum: hardness 9 (very hard).

Final Answer:
Talc