fourfold rotary inversion axis in c. Example: the meteorite mineral schreibersite (Fe,Ni)3P. 5 4/m, tetr.-dipyramidal:...Chap. 6), periclase, MgO, uraninite (7 Sect. 7.4), spinel, magnetite, chromite (7 Sect. 7.2), and the garnet...n Fluorite CaF2 1.434 Halite NaCl 1.544 Spinel MgAl2O4 1.714 Almandine garnet Fe2+3Al2[SiO4]3...of gypsum have been found in caves in Chihuahua, Mexico, where they formed by solution of anhydrite rock...been produced since 1905, followed by sapphire and spinel (1910), star ruby, star sapphire and rutile (1947/1948) |