Johannsenite, CaMn2+Si2O6 is a rare silicate mineral belonging to the pyroxene family, formed either in limestone or through metamorphic processes. It is often linked with lead-zinc mineralization and is considered relatively rare, although it is reported to be plentiful in Arizona's Aravaipa region. Typically, it appears as spherulite-like aggregates. Johannsenite is susceptible to oxidation, hydration, and carbonation, and it frequently undergoes alteration to rhodonite. The mineral was named in 1932 in honor of Albert Johannsen.
