A possible origin of malachite’s distinctive banding

In a new paper, published by American Mineralogist on 2nd April 2020, Dr Dominic Papineau (UCL Earth Sciences and The Centre for Planetary Sciences at UCL/Birckbeck) explains that oscillating chemical reactions could be responsible for the banding seen in Malachite because these have comparable geometric patterns and chemical composition to the bands formed using the classical reactants of the Belousov-Zhabotinsky (B-Z) reaction. The video shows the chemically-oscillating experiment, in a 10 centimetre diameter Petri dish on a LED light board, with orange ferroin redox indicator and the reactants of the classical Belousov-Zhabotinsky reaction. The grey-blue circular chemical waves are seen to diffuse away from randomly located oxidation spots over minutes times scales. Note that the destructive interference of the circular waves leads to the trace being erased when they meet, which is also a characteristic feature of botryoidal malachite.