Psilomelane is an umbrella term for hard black manganese oxide and is composed of hydrous manganese oxide with variable amounts of barium and potassium. The name, psilomelane comes from the Greek for "psilos" (smooth) and "melas" (black) because of its smooth, black appearance. Psilomelane is often layered with gray pyrolusite, giving it attractive gray bands and swirls. It is often traded as "Merlinite" or erroneously called "black hematite", though hematite is iron oxide. Psilomelane often forms with barite, quartz, hematite and jasper. When intergrown with jasper it is traded as "psilomelane jasper".
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