Question

Consider the following statements regarding Feldspar: Which of the statements above are correct?

1. It makes up more than 50% of the Earth's crust.
2. All varieties of Feldspar contain only Silicon and Oxygen.
3. It is used in the manufacturing of ceramics.

• A. All
• B. 1 only
• C. None of these
• D. 1, 3

Answer 1

Answer:

D. 1, 3

• Feldspar is a group of rock-forming tectosilicate minerals that make up about 41% of the Earth's continental crust by weight. This makes it the most abundant mineral group in the Earth's crust.
• Common varieties of feldspar are alkali feldspars (potassium or sodium rich) and plagioclase feldspars (sodium or calcium rich). They are aluminum silicate minerals containing varying amounts of potassium (K), sodium (Na), and calcium (Ca). Therefore, statement 2 is incorrect as it contains other elements besides Silicon and Oxygen.
• Feldspar is widely used in the manufacturing of ceramics and glass. It acts as a flux in the ceramic industry, lowering the melting point of silica and promoting vitrification. In glassmaking, it contributes alumina and alkali, improving the durability and chemical resistance of the glass.
• The major types of feldspar include plagioclase (e.g., albite, anorthite) and alkali feldspar (e.g., orthoclase, microcline, sanidine).
• Key applications in the ceramics industry include tiles, sanitaryware, and electrical porcelain.