GEOLOGY

Detailed explanation-1: -Talc (1), the softest mineral on the Mohs scale has a hardness greater than gypsum (2) in the direction that is perpendicular to the cleavage. Diamonds (10) also show a variation in hardness (the octahedral faces are harder than the cube faces).

Detailed explanation-2: -Talc is the softest mineral on Earth. The Mohs scale of hardness uses talc as its starting-point, with a value of 1. Talc is a silicate (like many of the Earth’s most common minerals), and in addition to silicon and oxygen, contains magnesium and water arranged into sheets in its crystal structure.

Detailed explanation-3: -Talc is the softest: it can be scratched by all other materials. Gypsum is harder: it can scratch talc but not calcite, which is even harder. Mohs’s scale of hardness is given below.

Detailed explanation-4: -Talc is the softest mineral on Earth. It is a silicate and it also contains magnesium and water arranged into sheets in its crystal structure.