manganite

noun

man·​ga·​nite ˈmaŋ-gə-ˌnīt 

1

: a metallic gray to black mineral MnO(OH) that is a hydroxide and minor ore of manganese

2

: any of various unstable salts made by reaction of manganese dioxide with a base

Word History

First Known Use

1827, in the meaning defined at sense 1