Talc is the softest known mineral which is why it has a Mohs hardness of 1. The Mohs Hardness Scale is the most popular way of measuring and testing the hardness of a mineral. The Mohs hardness ranges from 1 (softest) to 10 (hardest). The hardest mineral with a Mohs hardness of 10 is diamond.
Talc is a clay mineral composed of magnesium silicates commonly used in making powder, paint, cosmetics, and many other products.