This scale, not useful for minerals in an industrial setting but useful for milling and electronic devices, uses a porcelain streak plate. Ranging from 0 to 10, alkali metals score less than 1, corundum at 9, and diamond at 10. For 10 points, name this scale measuring the hardness of minerals, created by a German geologist.
a) Richter Scale
b) Kelvin Scale
c) Beaufort Scale
d) Mohs Scale