Polianite is a noun used to describe a rare mineral that belongs to the oxide group. It is also known as psilomelane and has a chemical formula of Ba(Mn+4,Mn+3)8O16(OH)4. This mineral usually occurs in massive to botryoidal (globular) aggregates and is commonly found in sedimentary rocks, particularly in manganese ore deposits.
Polianite typically exhibits a dark black, bluish-black, or iron-black coloration, often with a sub-metallic to dull luster. It has a hardness of 5 to 6 on the Mohs scale, indicating moderate hardness. Interestingly, it is dense and lacks notable cleavage.
When studied under a microscope, polianite can be seen to possess a dense radiating fibrous structure, which contributes to its distinctive appearance. This mineral is composed mostly of manganese oxides, with traces of barium and other elements present in its chemical composition.
Polianite can sometimes be associated with other manganese minerals like pyrolusite, hollandite, and braunite, contributing to the complexity of manganese-rich geological formations. It typically forms through the precipitation of manganese from aqueous solutions or from the alteration of other manganese minerals by chemical processes.
Although polianite does not have any significant industrial uses, it is extensively collected as a mineral specimen due to its striking color, crystal habit, and association with other valuable minerals.
