overgrowth by its darker colour that relates to its higher Fe content and its hexagonal shape, while it is completely...end-member compositions; another example is Mg and Fe in olivine. Crystallographic System & Point Group...to darker brown internal reflections) in a massive Fe-poor sphalerite (orange internal reflections), jordanite...rutile, and ulvöspinel separating from ilmenite). Fe-, Cu-, and Ag-containing sulfides are even more out...interstitial space. Examples include various Cr, Fe, and Ti oxides as well as sulfides, the latter crystallizing |