Lepidolite: Gemstone Information

Recent revision of minerals of the mica group has renamed lepidolite as ‘lepidolite’ (a series name). Mandarino & Back, Fleischer’s Glossary of Mineral Species, 2004 states ‘used for monoclinic trioctahedral micas on or close to the trilithionite-polylithionite join: light micas with substantial lithium  Various polytypes are known.’ For the purposes of this description the former name will be retained in order to avoid circumlocutions.Ornamental lepidolite is massive, fine-grained and a pale rose colour. It has been polished into various shapes despite the hardness of 3.5 and the easy and perfect cleavage. The SG is 2.5–4 and the RI (transparent to translucent material is sometimes faceted) for the alpha, beta and gamma rays is 1.525–1.548, 1.551–1.585, 1.554–1.587, biaxial negative with birefringence 0.018–0.038. The occurrence is chiefly, if not exclusively, in granite pegmatites, ornamental specimens coming from various sites in California and Maine, USA. Some of the transparent lepidolite comes from Brazil.