Size 7 x 5 x 4 cm - weight 132 grams A rare specimen Psilomelane with Jarosite crystals, the composition is completed by microcrystals of Azurite Malachite Gibbsite on the parent rock of Limonite. A complex rare mineral from the ancient mines of Lavrion From '' Εsperanza'' Mine, Agios Konstantinos, Lavrion mining district, Lavreotiki, East Attica, Greece Psilomelane - The name has reference to this characteristic appearance, from the Greek for (naked, smooth) and (black) Psilomelane is a group name for hard black manganese oxides including hollandite and romanechite. Psilomelane consists of hydrous manganese oxide with variable amounts of barium and potassium. will be sent with a security number