pewennite
Pewennite is a rare mineral discovered in 1994, named after the French mineralogist Pierre Pewennite. It is a complex oxide mineral with the chemical formula (Ba,Ca)2(Fe,Mn)5+O8. Pewennite is typically found in association with other minerals such as magnetite, hematite, and goethite in hydrothermal veins and skarns. It is known for its distinctive dark brown to black color and its metallic luster. The mineral has a hardness of approximately 5.5 on the Mohs scale and a specific gravity of around 4.5. Pewennite is of interest to mineralogists and collectors due to its rarity and unique chemical composition. It is not known to have any significant industrial applications.