Question

Aluminium occurs abundantly in the earth's crust in the form of aluminium silicates. Which of the following is not an alumino-silicate?

• A. Kaolin (China clay)
• B. Clay
• C. Mica
• D. Brookite

Answer 1

Answer: (D)

Brookite

Aluminosilicate minerals are minerals composed of aluminium, silicon, and oxygen, plus countercations. They are a major component of kaolin and other clay minerals. Andalusite, kyanite, and sillimanite are naturally occurring aluminosilicate minerals that have the composition $A{l}_{2}Si{O}_5$.

Brookite is the orthorhombic variant of titanium dioxide, $Ti{O}_2$, which occurs in four natural polymorphic forms (minerals with the same composition but different structure).

Hence option D is correct answer.