The composition of sapphire is :
MH SET - 2018, SET Exam - 2018,
Answer: A
Sapphire is \(\text{Al}_{2}\text{O}_{3}\), aluminium oxide.
Sapphire is a gem variety of the mineral corundum, coloured blue mainly by traces of iron and titanium; the red variety of the same mineral is ruby. Corundum's hardness of 9 on the Mohs scale makes it the hardest natural mineral after diamond.
\(\text{CaTiO}_{3}\) is perovskite, a calcium titanium oxide. \(\text{Al}_{2}\text{SiO}_{5}\) is the formula shared by the aluminosilicates kyanite, andalusite and sillimanite. The hydrous aluminium silicate in option D is not corundum either.
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