multapeite

Multapeite is a mineral belonging to the apatite group. Its chemical formula is Ca5(PO4)3(F, Cl, OH). The name multapeite was proposed by a team of researchers in 2019, reflecting the variable halogen content, often a mixture of fluorine, chlorine, and hydroxyl groups, within the mineral structure. It is essentially a fluorapatite, chlorapatite, or hydroxylapatite with mixed halogen occupancies. Multapeite typically forms in igneous rocks, particularly those that are alkaline and rich in phosphorus. It can also be found in metamorphic rocks and hydrothermal vein deposits. The color of multapeite can vary, ranging from colorless to white, yellow, or brown, often depending on the presence of impurities. Crystals are usually prismatic and can be found as individual grains or aggregates. Its hardness is similar to other apatites, typically around 5 on the Mohs scale, and it has a vitreous to greasy luster. Optical properties include birefringence and a refractive index that varies with the halogen composition. Multapeite is not a particularly common mineral and is primarily of interest to mineralogists and geochemists for understanding mineral formation processes and the behavior of halogens in geological environments.