 The feldspar has partly unmixed on the micro-scale to form a perthite, and the presence of the alternating alkali feldspar and plagioclase layers give its characteristic silver blue sheen (Schiller effect, labradorescence) on polished surfaces.Olivine can be present along with apatite, and locally quartz.Larvikite is usually rich in titanium, with titanaugite and/or titanomagnetite present.