Be3Al2SiO36O

Be3Al2Si6O18, also known as bertrandite, is a rare mineral species composed of beryllium, aluminum, silicon, and oxygen. It was first discovered in 1906 in the Iron Mountain town area of Shasta County, California, USA. Bertrandite is a silicate mineral and is characterized by its chemical formula, which indicates a probable orthosilicate structure.

Bertrandite has a monoclinic crystal system and is typically found in convergent metamorphic environments, particularly in granulite facies rocks. Its crystallographic structure can be adequately described by a prismatic crystal form, often displaying pinacoid faces. This mineral's properties are determined by a relatively unusual combination of atoms within its crystal lattice, leading to unique physical and optical characteristics.

The mineral's color is often white or yellowish-white, while its transparency can range from transparent to opaque. Mohs hardness is 7.5-8 on the scale, and be3Al2Si6O18 exhibits a vitreous luster. Bertrandite's chemical stability is notable for a silicate mineral, especially in terms of its beryllium content, but oxidation may lead to weathering. Due to the mineral's relatively widespread geographic distribution and potentially significant beryllium content, bertrandite has become an important source constituent of beryllium ores.