Final answer:
The statement is false because the Mohs scale is qualitative and does not indicate that a mineral with a hardness of 8 is quantitatively twice as hard as one with a hardness of 4.
Step-by-step explanation:
The statement that Topaz, which has a hardness of 8 on the Mohs scale, is twice as hard as fluorite, which has a hardness of 4 on the Mohs scale, is false. The Mohs scale of mineral hardness is qualitative, meaning the scale does not represent a linear or quantitative measure of hardness. Rather, it is based on the relative ability of one mineral to scratch another. Therefore, a mineral with a Mohs hardness of 8 is not quantitatively twice as hard as a mineral with a hardness of 4.