Lithium-bearing mica with composition K₂(Li,Al)_5–6 [Si_6–7Al_2–1O₂₀] (OH,F)₄; sp. gr. 2.8–2.9; hardness 2.5–4.0; monoclinic; crystals as small flakes; perfect basal {001} cleavage; lilac to greyish; occurs in late-stage pegmatites associated with other lithium minerals, such as spodumene, and minerals of a pneumatolytic origin, such as tourmaline and topaz. Lepidolite is an important ore mineral of lithium.