This mineral's uniaxial, hexagonal crystals are classified by the space group R-3c and the point group D3D ["D-sub 3-D"].
This mineral's uniaxial, hexagonal crystals are classified by the space group R-3c and the point group D3D ["D-sub 3-D"]. Synthetic examples of this mineral may be created by reacting barium fluoride with its main constituent in a flame-fusion process named for Verneuil. When this mineral possesses an orange-red color, it is referred to as "padparadscha". The presence of (*) titanium and iron give this hematite-group mineral a blue appearance, and chromium impurities in this mineral result in it gaining a distinct red color. For 10 points, name this aluminum oxide-based mineral with a Mohs hardness of 9 that is found in gemstones like rubies and sapphires. 
This mineral's uniaxial, hexagonal crystals are classified by the space group R-3c and the point group D3D ["D-sub 3-D"].
corundum [prompt on sapphires or rubies]