Martian manganese continues to fascinate. Its mere existence on Mars brings up a host of questions about environmental conditions in the past and present, and also what it might signify in ancient rocks on Earth. It would be great to get this stuff into one of our Perseverance tubes!
So what’s so great about manganese? Manganese minerals have long been used as an indicator of redox conditions—that is, they tell us about a type of powerful chemical reaction that often involves oxygen. When we see manganese minerals on Earth, they tell us that not only was there liquid water, but also there must have been strong oxidants present—or microbes doing related chemistry. When we see manganese minerals on Mars, we may then ask whether they formed by some unusual oxidizing chemistry unique to the martian environment, or whether like on Earth, they may be pointing to the past presence of oxygen or life.