(Zn,Fe,Mn)Mn₃O₇.3H₂O

This sample of chalcophanite is displayed in the Smithsonian Museum of Natural History. Chalcophanite is an oxide mineral which contains zinc and manganese with the composition (Zn,Fe,Mn)Mn₃O₇.3H₂O. The sample at left is about 14 cm across and is from Sterling Hill mine, Ogdensburg, New Jersey.