Pyroxene weathers to produce: (A) Silica (B) Fe-oxides (C) Bicarbonate ion (D) Smectite (E) Kaolinite
Choose the correct answer from the options given below:

Correct option is C

Explanation The correct answer is (c) A, B, and C only. When pyroxene minerals weather, they commonly produce the following:
1. (A) Silica (SiO₂):
· Pyroxenes are silicate minerals, and during weathering, silica is released as part of the breakdown process.
2. (B) Fe-oxides:
· Iron-bearing pyroxenes (e.g., augite) weather to form iron oxides like hematite or goethite.
3. (C) Bicarbonate ion (HCO₃⁻):
· Carbonic acid from water and CO₂ reacts with pyroxene, producing bicarbonate ions in the solution.
Why (D) Smectite and (E) Kaolinite are Incorrect:
· Smectite (D):
· While smectite is a common clay mineral produced from the weathering of certain silicates, it is not a typical direct product of pyroxene weathering.
· Kaolinite (E):
· Kaolinite typically forms from the weathering of feldspar or micas, not pyroxenes.
Information Booster 1. Pyroxene Group:
· Includes minerals like augite, diopside, and enstatite.
· Common in igneous and metamorphic rocks.
2. Weathering of Pyroxenes:
· Chemical weathering processes like hydrolysis, oxidation, and carbonation contribute to the breakdown of pyroxenes.
3. Key Weathering Products:
· Silica: Released in aqueous solution.
· Fe-oxides: Formed through oxidation of iron-rich minerals.
· Bicarbonate Ions: Produced from carbonic acid reactions.
Additional Knowledge · Silicate Weathering:
· Plays a crucial role in the global carbon cycle by consuming CO₂ and producing bicarbonate ions.
· Iron Oxides:
· Important components of soils and sediments that give them a characteristic red or yellow color.