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SPODUMENE

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Originally appearing in Volume V25, Page 712 of the 1911 Encyclopedia Britannica.
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SPODUMENE , a See also:

lithium-See also:aluminium silicate belonging to the See also:pyroxene See also:group (see PYROXENE). It was named by B. J. d'See also:Andrada e Sylva, in 'boo, from Gr. a'r63sec (ash-coloured), in allusion to its See also:grey See also:colour. Soon afterwards J. R. Ha-0y termed it tripltane, because it exhibited certain characteristics equally in three directions (Tpicbavifs, appearing three-See also:fold). Spodumene crystallizes in the See also:monoclinic See also:system, the crystals having generally a prismatic See also:habit and being often striated longitudinally. It has perfect prismatic cleavage, and imperfect cleavage parallel to the clinopinacoid, whilst a lamellar structure may be See also:developed by parting along the orthopinacoid. The hardness is 6.5 to 7, and the specific gravity about 3.16. Though generally a dull See also:mineral, some varieties of spodumene are so brightly coloured and transparent as to be valued as See also:gem-stones. Such is the See also:emerald-See also:green See also:hiddenite (q.v.) and the See also:lilac-coloured See also:kunzite (q.v.), whilst a yellow or yellowish-green spodumene found as pebbles in the See also:state of See also:Minas Geraes, in See also:Brazil, resembles, when cut, some kinds of See also:chrysoberyl. See also:Common spodumene is used as a source of lithium in chemical pteparations.

Spodumene occurs in See also:

granite and crystalline See also:schists. The See also:original specimens came from the isle of Uto in Sodermanland, See also:Sweden, but the finest examples are found in the See also:United States, especially in See also:Massachusetts, where See also:Goshen, See also:Sterling and See also:Chester-See also:field are well-known localities. Very See also:fine specimens have been obtained from the See also:Black Hills of S. Dakota. Some remarkable deposits containing spodumene were discovered many years ago at Branchville, See also:Fairfield See also:county, See also:Connecticut, and the minerals which they yielded were exhaustively studied by See also:Professor G. J. See also:Brush and E. S. See also:Dana. The spodumene occurred in large quantity, in a vein of See also:albite-granite, associated with See also:apatite, See also:garnet, See also:columbite, See also:pitchblende and other See also:uranium minerals, together with several See also:species of See also:manganese See also:phosphates, termed eosphorite, triploidite, dickinsonite, lithiophilite, natrophilite, reddingite, fairfieldite and fillowite. The spodumene, which has normally the See also:formula LiAl (SiO3)2, becomes altered at Branchville to what has been called #-spodumene, which consists really of the mineral eucryptite (LiAlSiO4) and albite. Eucryptite was named by Brush and Dana from eu (well) and spurs-Os (concealed).

Further alteration results in the formation of cymatolite, a mineral described by C. U. Shepard in 1867, but shown to be an intimate See also:

mechanical mixture of See also:muscovite and albite. The final products of alteration of the spodumene may be muscovite, albite and See also:microcline. The mineral discovered in 1817 in the granite of Killiney See also:Hill, near See also:Dublin, and described by T. See also:Thomson as killinite, appears to be an altered spodumene. (F. W.

End of Article: SPODUMENE

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