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Brief Description: Its chemical formula is NaAlSi2O6 and it belongs to the category Inosilicate minerals (pyroxene). Its lustre is vitreous. Its colour is green, white, bluish-grey or greyish-green. Transparent to semitransparent. Its specific gravity is 3.3 and its hardness 6.5. Crystal system: monoclinic. It is used as a gemstone. 
Bibliography: Ευρετήριο ορυκτών ΑΠΘ στην ιστοσελίδα http://www.geo.auth.gr/106/az_gr.htm Berry, L.G., Mason, B. and Dietrich, R.V. (1983). Mineralogy. W. H. Freeman and Company, San Francisco, 561 pp.