The search for a crystalline matrix that promotes stabilization of the rare oxidation states of manganese and chromium ... have a persistent green or blue color (or their intermediate shades).

Figure 1: Possible pathways and states of the manganese centre of Mn-porphyrins during their reaction with O 2 or with the single oxygen donor PFIB. Figure 4: Reaction of Mn–porphyrins with ...

On Earth, manganese becomes enriched because of oxygen in the atmosphere, and this process is often sped up by the presence of microbes. Microbes on Earth can use the many oxidation states of ...