ˌpīrəˈlüˌsīt noun
( -s )
Etymology: German pyrolusit, from pyr- + Greek lousis washing (from louein to wash) + German -it -ite; from its use as glass soap — more at lye
: a mineral MnO 2 that is of an iron-black or dark steel-gray color and metallic luster usually soft native manganese dioxide and is the most important ore of manganese — see glass soap