In other cases, quartz and iron oxides, limonite, goethite, and jarosite, exist as pseudomorphs, replacing the pyrite and primary ore minerals. Frequently, gossan appears as a red "stain" against the background rock and soil, due to the abundance of oxidized iron; the gossan may be a topographic positive area due to the abundance of erosion-resistant quartz and iron oxides. Although most gossans are red, orange, or yellow, black gossans from manganese oxides such as pyrolusite, manganite, and especially psilomelane form at the oxidized portion of manganese-rich mineral deposits.