NATURAL MATERIALS SCIENCE: EXPLORING THE CHEMISTRY BEHIND THE MOHS HARDNESS SCALE

Minerals are as diverse and complex visually as they are chemically. Cleavage, color, stability, and even magnetic properties are all a direct consequence of their atomic structure. Most geology students are required to take an introductory chemistry course, but many fail to retain or constructively apply those concepts to petrological or geochemical courses later in their education. Knowing the elemental composition of a mineral can only get one so far in assessing mineral properties, as can be seen in the stark contrast between graphite and diamond.

The study of mineralogy combines geology and chemistry to teach us about our planet’s natural materials and Earth processes, as well as inspire geologists and chemists to craft novel solutions for sustainable energy and environmental applications. With mineralogy taught in a way which actively challenges a geologist to apply their chemistry education, students can enhance their understanding of why minerals vary in behavior and mechanical properties. In addition, opportunities like this which strengthen their chemistry knowledge better prepare students for more advanced geochemical understanding.

A simple way that chemistry can be incorporated within a mineralogy course is through providing students with a conceptual chemical framework for the Mohs Hardness Scale. The Mohs Hardness Scale was published almost 200 years ago and is still used to teach introductory geology students about mineral properties. By evaluating the minerals of the Mohs Hardness Scale sequentially from 1(softest) to 10(hardest) based on their structure and atomic interactions, the scale can serve as a simple demonstration of the importance of chemical bonds, attractive forces, atomic packing, and lattice structure. This presentation will explore how modern chemical concepts can be used in teaching about this centerpiece of introductory geology labs.