Friedrichbeckeite
Friedrichbeckeite is an IMA-recognized mineral species in the silicate class, with the chemical formula K( Na)Mg₂(Be₂Mg)Si₁₂O₃₀.
It crystallizes in the hexagonal crystal system (space group P6/mcc). It is a member of the Milarite structural group.
Key properties: Mohs hardness 6; specific gravity 2.686; Colorless to pale cream streak; Vitreous luster; optically uniaxial.
IMA symbol Fri, IMA status: approved, named in 2008.
Found in vesicles in pyrometamorphically metasomatized silicate-rich xenoliths in leucite- tephrite volcanic rock.
It is found associated with Tridymite, augite, magnesiohornblende, enstatite, almandine-spessartine garnet, fluorapatite, biotite, braunite, hematite, roedderite.
The mineral was named to honor Austrian mineralogist and petrographer Friedrich Johann Karl Becke (1855–1931), best known for developing the Becke-line method for determining indices of refraction.