polianite
/ˈpəʊlɪənʌɪt/Mineralogy
noun
A mineral containing manganese, formerly regarded as a variety of pyrolusite but now generally regarded as identical with it.
Origin
Mid 19th century; earliest use found in James Nicol (1810–1879), geologist. From German Polianit from ancient Greek πολιά greyness + German -it, so called on account of its colour.