Its specific gravity is high, about 4, and it occurs in hexagonal crystals. Titanium atoms embedded in crystals of it are used as a gain medium to produce tunability over a several hundred nanometer range in lasers. Impurities in it in the form of rutile needles aligned with
Its specific gravity is high, about 4, and it occurs in hexagonal crystals. Titanium atoms embedded in crystals of it are used as a gain medium to produce tunability over a several hundred nanometer range in lasers. Impurities in it in the form of rutile needles aligned with its crystal faces can lead to asterism. Synthetic samples can be made with the Verneuil process. Historically, it was the object of British mining operations in southeast Asia and used as an abrasive, sometimes as a component of emery. It is a form of aluminum oxide, Al2O3. Gems of it that gain a red color due to chromium are known as rubies, and other colors are sapphire. For 10 points, what is this mineral that is number 9 on the Mohs scale of hardness?
Its specific gravity is high, about 4, and it occurs in hexagonal crystals.
corundum [accept sapphire until "abrasive"]