Wedgetite

Wedgetite is a rare and poorly understood mineral that belongs to the class of sulfides. It was first described in 1967 from specimens found in the Wedgetail mine, near Broken Hill, New South Wales, Australia. The mineral was named after its type locality, the Wedgetail mine, which is also known for producing other unusual minerals such as duftite and bismuthinite.

Wedgetite has the chemical formula PbBi₂S₄, indicating it contains lead (Pb), bismuth (Bi), and sulfur (S). Its crystal structure is complex, belonging to the orthorhombic crystal system, though it often forms as anhedral grains or crusts rather than well-defined crystals. The mineral typically exhibits a metallic luster and a dark gray to black color, with a streak that ranges from gray to black. Wedgetite has a Mohs hardness of approximately 2.5, making it relatively soft compared to many other sulfide minerals.

Occurrences of wedgetite are extremely limited, with the type locality in Australia being one of the few known locations where it has been identified. It is often found in association with other sulfide minerals such as galena, sphalerite, and bismuthinite, typically in hydrothermal vein deposits. Due to its rarity and the difficulty in distinguishing it from similar minerals, wedgetite is not commonly encountered in collections or research.

The mineral’s properties and occurrence have been studied primarily through its type locality, with limited additional reports from other regions. Its formation is thought to be related to low-temperature hydrothermal processes involving bismuth-rich fluids. Wedgetite remains an interesting subject for mineralogists due to its unique composition and scarcity.