Lepidolite (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."Manual of Mineralogy, 20th Ed." by Cornelius Hurlbut and Cornelis Klein. 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.H.