Ca2Mg2Si2O7

Ca2Mg2Si2O7 is a mineral belonging to the melilite group, which are silicates with the general formula (Ca,Na)2(Mg,Fe,Al)3(Si,Al)3O7. Specifically, Ca2Mg2Si2O7 is known as akermanite. It is a relatively rare mineral, typically found in alkaline igneous rocks, particularly in phonolites and related volcanic rocks, as well as in some metamorphic settings like skarns. Akermanite crystallizes in the tetragonal crystal system, often forming short prismatic crystals or granular aggregates. Its color can vary from colorless to white, gray, or pale yellow, and it is transparent to translucent. The mineral possesses a vitreous luster and a Mohs hardness of approximately 5.5 to 6. Its specific gravity is around 2.9 to 3.0. Akermanite is isostructural with gehlenite (Ca2Al2SiO7) and åkermanite is the magnesium-rich endmember of the akermanite-gehlenite solid solution series. When pure, akermanite has a distinct chemical composition with calcium, magnesium, silicon, and oxygen in a specific ratio. It can exhibit fluorescence under ultraviolet light. Its formation is generally associated with magmas poor in silica and rich in alkalis and alkaline earth elements.