Which mineral produces the most clay minerals during chemical weathering processes?

• A. Feldspar
• B. Quartz
• C. Gypsum
• D. Calcite

Answer: (A)

Clay minerals form mainly through chemical weathering by hydrolysis of feldspar. Feldspar has a framework of silica and aluminum with alkali or alkaline-earth cations that are relatively easily removed when exposed to water and acidic conditions. As these ions are removed, silica and aluminum reorganize to form layered aluminosilicate structures that become clay minerals such as kaolinite, illite, or smectite. Feldspar is particularly reactive in weathering environments, so it contributes the most to clay production.

In contrast, quartz is highly resistant to chemical weathering and tends to persist as grains rather than form clays. Gypsum and calcite dissolve readily to soluble ions (calcium, sulfate, carbonate) and do not commonly yield clay minerals as their primary weathering products.