Lepidolite is a lilac-gray or rose-colored lithium-bearing mineral of the mica group. It is associated with other lithium-bearing minerals like spodumene in pegmatite bodies. The mineral is noteworthy as one of the major sources of the rare alkali metals rubidium and caesium.
When lepidolite was first discovered in the 1700s, it was given the name lilalite, for its lavender color. Scientists eventually renamed the stone lepidolite, from the Greek lepidos meaning "scale". The reference is to the scaly appearance of lithium flakes in the mineral.
By composition, lepidolite is potassium lithium aluminum silicate hydroxide fluoride. It has a specific gravity of approximately 2.8 and a refractive index of 1.525 - 1.548. Lepidolite has a hardness rating of 2.5 on the Mohs scale and perfect cleavage in one direction. Lepidolite ranges in color from lilac-gray to rose; it is the presence of lithium that lends it the distinctive color. It has a vitreous to pearly luster. Typically lepidolite is found in massive form with uniformly indistinguishable crystals forming large masses.
Lepidolite is a major source of the element lithium, the world's lightest metal. Lithium has many important industrial applications: it is used in rechargeable batteries, alloys for aircraft parts, and in appliances like toasters and microwave ovens. Lithium compounds are used in mobile phones, air purifiers, high-temperature lubricants, and mood-stabilizing drugs.
Noteworthy deposits have been found in Brazil, Russia (the Ural Mountains), California (San Diego County), Mexico, Canada (Tanco Pegmatite at Bernic Lake in Manitoba), Madagascar and Zimbabwe.
- First Published: March-30-2009
- Last Updated: August-22-2014
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