Astusite

Astusite is a rare and unique mineral that was first discovered in the late 19th century. It is named after the type locality, the Astus mine in Sardinia, Italy. Astusite is a complex oxide mineral with the chemical formula (Fe,Mn)2O3. It is typically found in association with other iron and manganese oxides, such as hausmannite and braunite.

Astusite crystals are usually small and prismatic, often forming aggregates or crusts. The mineral is typically dark brown to black in color, with a metallic luster. It has a hardness of approximately 5.5 on the Mohs scale and a specific gravity of around 4.8.

The mineral is of limited economic importance, but it has been studied for its potential use in various industrial applications. Astusite's complex crystal structure and unique properties make it an interesting subject for mineralogists and materials scientists. It is also a popular specimen for collectors due to its rarity and distinctive appearance.