etturite
Etturite is a theoretical mineral composed of calcium, aluminum, silicon, oxygen, and fluorine. Its chemical formula is Ca2Al2(Si2O7)F2. It is a member of the sorosilicate group, meaning its silicate tetrahedra are linked in pairs. The theoretical mineral was proposed to exist in high-temperature, fluorine-rich environments, such as within certain igneous rocks or hydrothermal veins. Etturite is structurally similar to the mineral larsenite, which has a formula of Ca2Zn2(Si2O7)F2. Research into etturite has primarily been conducted through crystallographic modeling and theoretical calculations. No natural occurrences of etturite have been definitively confirmed or widely accepted by the mineralogical community. Its existence remains speculative, and it is not listed in standard mineral databases as a recognized species. Further experimental work or the discovery of a natural sample would be required to validate its status as a distinct mineral.