minette
/mɪˈnɛt/noun
1 Geology. A dark-coloured lamprophyre consisting chiefly of biotite and alkaline feldspars.
2 Geology. More fully minette ironstone, minette ore. A low-grade oolitic iron ore found mainly in Luxembourg and Lorraine, France.
Origin
Mid 19th century. In sense 1 from German Minette from French minette low-grade iron ore found chiefly in Lorraine from mine + -ette.