Abstract
Microprobe analyses were carried out on Mn-rich amphiboles in a quartz schist from the Iimori mine, Wakayama Prefecture, Japan. The amphiboles are chemically heterogeneous within single grains. Their compositions vary from magnesio-riebeckite to suenoite (manganocummingtonite) with Mn at the M4 site = 0.00-1.81 apfu.