ALEXANDRITE  , a variety of

chrysoberyl (q.v.) discovered in the Urals in 1833, on the day set apart for celebrating the majority of the cesarevich, afterwards the tsar, Alexander II., in whose honour the stone was named by Nils Gustaf Nordenskiold, of Helsingfors . It is remarkable for being strongly dichroic, generally appearing dark green by daylight and raspberry-red by candle-light, or by daylight transmitted through the stone . As red and green are the military colours of Russia, the mineral became highly popular as a gem-stone . The dark green crystals are usually cloudy and cracked, and grouped in triplets presenting a pseudo-hexagonal form . Alexandrite was found originally in the emerald- mine of Takovaya, east of Ekaterinburg in the Urals, and afterwards in the gold-bearing sands of the Sanarka in the southern Urals . Subsequently it was discovered in greater abundance in the gem-gravels of Ceylon . It has been found also in Tasmania . Some of the Ceylon alexandrite exhibits, when suitably cut, the Cat's-eye chatoyance, whence it has been called alexandrite cat's-eye . (F . W .