_Crystalline System_: Orthorhombic. _Hardness_: 8.5. _Lustre_: Vitreous. Transparent to translucent. _Refraction_: Double. _Chemical Composition_: Alumina 80.2. Glucina 19.8. _Chemical Symbol_: BeAl_{2}O_{4}. _Specific Gravity_: 3.7-3.86. _Dichroism_: Strong in Alexandrite. Distinct in Chrysoberyl. _Properties_: Crystals exhibit remarkable twinning at times. Chrysoberyl is highly electric and when submitted to frictional agitation holds electricity for a long time. Not affected by acids. Under the blowpipe it is unaltered and infusible, but it fuses tardily with borax or microcosmic salt. The Alexandrite variety which, as Professor J. G. Dana says, bears the same relation to ordinary Chrysoberyl as Emerald to Beryl, displays curious changes of colour from leafy green to raspberry red in real and artificial lights. _In the Zodiac_: Chrysoberyl is under the Heavenly Pisces; Alexandrite is under the Heavenly Aquarius. _Where found_: Ceylon, Brazil, Russia, Ireland, Australia, etc. CORUNDUM SAPPHIRE, RUBY, ORIENTAL AMETHYST, ORIENTAL EMERALD, ETC. _Crystalline System_: Rhombohedral. _Hardness_: 9. _Lustre_: Transparent to translucent. _Refraction_: Moderately double. _Chemical Composition_: Aluminium 53-53.2. Oxygen 46.8. _Chemical Symbol_: Al_{2}O_{3}. _Specific Gravity_: 3.90-4.16. _Dichroism_: Strong. _Properties_: Submitted to friction exhibits electrical properties which withdraw very slowly. Acids do not affect Corundum, but under the blowpipe in borax or microcosmic salt it gradually melts to a transparent globule. Radium influences the colour strongly, so much indeed as to impart it in achromatic specimens. The stone is variously affected by heat. Treated by Sir William Crooks by exposure to high tension electric currents in a similar way to the diamond the ruby phosphoresced with an intense red light, and the sapphire with an intense blue. Dr. T. Coke Squance of Sunderland, well-known in connection with radio-therapeutical research, has succeeded in transforming a faint pink sapphire into a fine ruby. During the process of transformation the lustre of the stone was so intensified that it nearly assumed the brilliancy of a diamond. Dr. Squance observed that both radium and X-rays cause a diamond to glow with a green light. “Besides the diamond,” he says, "a mineral called Kunzite glows with a lovely red hue. I submitted a sapphire to the Radium rays for a long period and it turned to a glorious red. In fact, it had become a ruby. I have similarly transformed other stones, a faint green sapphire, for instance, turning into an oriental emerald." Sir William Crooks noted the sage-green colour of the diamond under Radium, but found that the colour could easily be removed by mechanical means. _In the Zodiac_: Blue and green sapphires are under the Heavenly