Unformatted text preview: harder substance will scratch, or cut into, a softer one. In order to establish a common system for determining hardness, Friedrich Mohs (1773-1839), a German mineralogist, developed a reference scale of mineral hardness. The Mohs scale of hardness (Figure 1.14), widely used today by geologists and engineers, utilizes ten index minerals as a reference set to determine the hardness of other minerals. The hardness value of 1 is assigned to the softest mineral in the set, talc, and 10 is assigned to the hardest mineral, diamond. Higher-numbered minerals will scratch lower-numbered minerals. For example, quartz, with a hardness of 7, will scratch calcite, which has a hardness of 3. It should be remembered that Mohs scale is a relative ranking and does not imply that mineral number 2, gypsum, is twice as hard as mineral 1, talc....
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