Manganite MnO(OH) is most commonly found as amorphous crusts and precipitates like in weathered rocks and surface soils. It more rarely occurs as slender, prismatic crystals, often fibrous or striated, in voids or open veins in volcanic rocks. Here seen in a radially twinned setting from a long-standing location near Ilfeld in the German Harz Mountains. Actual size is 90 mm.