Garnieriite

Garnieriite is a rare mineral with the chemical formula (Na,Ca)2Mn3+3(PO4)2(OH)3. It was first discovered in 1977 in the Garnierite mine in the French Alps, from which it derives its name. Garnieriite is a member of the whitlockite group of minerals, which are characterized by their phosphate structure. It typically forms as a secondary mineral in phosphate-rich environments, often associated with other manganese minerals such as rhodonite and braunite.

The mineral is known for its distinctive deep red to brown color, which is due to the presence of trivalent manganese (Mn3+). Garnieriite crystals are usually small and prismatic, often found in radiating or divergent aggregates. It has a hardness of approximately 5 on the Mohs scale and a specific gravity of around 3.5. Garnieriite is not commonly found in large quantities and is primarily of interest to mineral collectors and researchers studying phosphate minerals.