A mineral scratches a copper penny, but is scratched by a steel nail. This means that the mineral is harder than the penny, but softer than the nail. The hardness of the mineral can be "bracketed" between the known hardness of the testing materials. How hard is the mineral according to the Mohs Hardness Scale?
a. Between 2.2 and 3.2
b. Between 3.2 and 5
c. Between 5 and 5.5
d. Between 5.5 and 7
e. ≥7