Lepiolite (KLi2Al(Al,Si)3O10(F,OH)2) is a lilac or rose-violet colored phyllosilicate mineral of the mica group that is a secondary source of lithium. It is associated with other lithium-bearing minerals like spodumene in pegmatite bodies. It is one of the major sources of the rare alkali metals, rubidium and caesium. In 1861 Robert Bunsen and Gustav Kirchhoff extracted 150 kg of lepidolite and yielded few gramms of rubidium salts for analysis, and therfore discovered the new element rubidium.