Answer: Talc is the softest and diamond is the hardest. Each mineral can scratch only those below it on the scale.
I'll Give a explaination.
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. The softness of talc and its perfect cleavage in one direction both owe to weak chemical bonds between adjacent sheets, which can be easily disrupted by scratching or shearing