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LEPIDOLITE

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Originally appearing in Volume V16, Page 464 of the 1911 Encyclopedia Britannica.
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LEPIDOLITE , or LITHIA-See also:

MICA, a See also:mineral of the mica See also:group (see Mica). It is a basic See also:aluminium, See also:potassium and See also:lithium fluo-silicate, with the approximate See also:formula KLi [Al(OH,F)2] Al(SiO3)3. Lithia and See also:fluorine are each See also:present to the extent of about 5%; See also:rubidium and See also:caesium are sometimes present in small amounts. Distinctly See also:developed See also:monoclinic crystals or cleavage sheets of large See also:size are of rare occurrence, the mineral being usually found as scaly aggregates, and on this See also:account was named lepidolite (from Gr. XE7ric, See also:scale) by M. H. See also:Klaproth in 1792. It is usually of a See also:lilac or See also:peach-blossom See also:colour, but is sometimes greyish-See also:white, and has a pearly lustre on the cleavage surfaces. The hardness is 21-4 and the sp. gr. 2.8-2.9, the optic axial See also:angle See also:measures 500-700. It is found in See also:pegmatite-See also:veins, often in association with See also:pink See also:tourmaline (See also:rubellite) and some-times intergrown in parallel position with See also:muscovite. Scaly masses of considerable extent are found at Rozena near Bystrzitz in See also:Moravia and at Pala in See also:San Diego See also:county, See also:California.

The material from Rozena has been known since 1791, and has some-times been cut and polished for ornamental purposes: it has a See also:

pretty colour and spangled See also:appearance and takes a See also:good See also:polish, but is rather soft. At Pala it has been extensively See also:mined for the preparation of lithium and rubidium salts. Other localities for the mineral are the See also:island of UtS in See also:Sweden, and See also:Auburn and See also:Paris in See also:Maine, U.S.A.; at Alabashka near Mursinka in the Urals large isolated crystals have been found, and from Central See also:Australia transparent cleavage sheets of a See also:fine lilac colour are known. The lithium-See also:iron mica zinnwaldite or lithionite is closely allied to lepidolite, differing from it in containing some ferrous iron in addition to the constituents mentioned above. It occurs as greyish silvery scales with hexagonal outlines in the See also:tin-bearing granites of Zinnwald in the See also:Erzgebirge, Bohemia and of See also:Cornwall. (L. J.

End of Article: LEPIDOLITE

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