Chemistry of colour (the colour of cobalt)

Description

This video mini-lecture was made for the 2023-2024 ITC teacher-of-the-year award (www.ITC.nl), for which I was nominated. It's about one of the key processes that causes colour of minerals in rocks, and therefore has relevance for all kinds of remote sensing, especially geological remote sensing: excitation of electrons in the 3d subshell of transition metals. Here I use ligand-field theory (in a very simple form) to discuss why cobalt-bearing minerals and compounds can be blue or pinkish-red.