vauxite

Vauxite is a rare phosphate mineral with the chemical formula AlFe³⁺⁴(PO₄)₂(OH)₂·8H₂O. It is known for its distinctive color, typically ranging from yellow to orange or reddish-brown. Vauxite is an hydrated aluminum iron phosphate hydroxide. It belongs to the vauxite group of minerals, which are characterized by their layered structures. The mineral typically forms as small, prismatic crystals, often found in association with other phosphate minerals.

The type locality for vauxite is the TipTop mine in the Black Hills of South Dakota, USA, where it was first described in 1922. It has also been found in other locations worldwide, though often in limited quantities. Vauxite is considered a secondary mineral, meaning it forms as a result of the weathering or alteration of other minerals. Its formation environment is typically in pegmatites or hydrothermal veins, where phosphate-rich fluids interact with aluminum and iron-bearing rocks. Due to its rarity and small crystal size, vauxite is primarily of interest to mineral collectors and researchers rather than having significant industrial applications.