PSILOMELANE is a general term for massive, hard manganese oxides.
CHEMISTRY (Ba,H2O)Mn10O20
CRYSTAL GROWTH AND HABITS Psilomelane is commonly massive, botryoidal, stalactitic and can also be found as earthy crusts or massive.
COLOR AND OTHER OPTICAL PROPERTIES Black to steel gray
HARDNESS 5 - 6
SPECIFIC GRAVITY 3.3 - 4.7
LUSTER Satiny to dull and earthy
STREAK Black to brownish black
BREAKABILITY Psilomelane has an uneven fracture and is brittle.
OCCURRENCE Psilomelane is found as a secondary mineral in the oxidized zone of manganese deposits.
ASSOCIATED MINERALS Pyrolusite, manganite
NAME From the Greek "psilo" for smooth and "melane" for black.