Given the task definition and input, reply with output. In this task you will be given a text passage from a trivia quiz. You should choose the category this question belongs to from these categories: History, Science, Social Science, Fine Arts, Literature. You can only choose one category, so if in doubt, please choose the closest match.

It frequently weathers into other minerals like margarite, zoisite, and kyanite. Produced by the Verneuil Process, it has been largely replaced in industrial applications by synthetic materials like alumina. When mixed with iron oxides and other minerals it is known as emery, and its finer varieties include sapphire and ruby. A naturally occurring aluminum oxide mineral with formula Al2 O3, FTP, what is this mineral whose Mohs hardness of 9 makes it the second hardest natural substance
Science