Which process changes the minerals' chemical composition in rocks?

• A. Chemical Weathering
• B. Physical Weathering
• C. Biological Weathering
• D. Mechanical Weathering

Answer: (A)

Chemical weathering is the process that changes the minerals' chemical composition in rocks. It happens when minerals react with water, acids, and oxygen, transforming them into new substances or dissolving ions. For example, feldspar reacts with water and carbon dioxide to form clay minerals and dissolved silica, iron-bearing minerals oxidize to iron oxides, and calcite dissolves in acidic rainwater. Physical or mechanical weathering breaks rocks into smaller pieces without changing their minerals’ chemistry, and while biological activity can contribute to chemical changes, the term chemical weathering specifically describes alterations in mineral composition.