NCERT Question 1(i)

Which one of the following minerals is formed by decomposition of rocks, leaving a residual mass of weathered material?

(a) coal

(b) bauxite

(c) gold

(d) zinc

Answer:

(b) Bauxite ✅

Explanation:

Bauxite is formed through the weathering and decomposition of rocks. This process removes soluble materials, leaving behind a residual deposit rich in aluminum. Over time, due to chemical weathering, aluminum-rich minerals accumulate, forming bauxite.

Points:

• Residual mineral: Formed in place by rock weathering.
• Rich in aluminum: Used for aluminum extraction.
• Common in tropical regions: Found in India, Australia, and Brazil.

Bauxite is an important ore of aluminum and is primarily formed through rock decomposition, making it a residual mineral deposit. 🌍⛏️