Question

The correct sequence of the decreasing order of the weathering stability of following minerals in a sedimentational motif is:
A. Muscovite,
B. Quartz,
C. Olivine,
D. Hornblende. Choose the correct answer from the options given below:

• A. B, A, D, C
• B. A, B, C, D
• C. B, C, D, A
• D. A, D, C, B

Hint:

Quartz is highly stable during weathering, while olivine is one of the least stable common silicate minerals.

Answer 1

The Correct Option is A

Concept:
Weathering stability of minerals depends on their resistance to chemical and physical weathering. Minerals formed at lower temperature are generally more stable at the Earth's surface, while high-temperature minerals weather faster.

Step 1: Identify the most stable mineral.
Quartz is highly resistant to weathering because it has a strong silicon-oxygen framework structure. \[ \text{Quartz}=\text{most stable} \] So, \[ B \text{ comes first} \]

Step 2: Compare muscovite and hornblende.
Muscovite is a mica mineral and is more stable than hornblende during weathering. \[ \text{Muscovite}>\text{Hornblende} \] So, \[ A \text{ comes before } D \]

Step 3: Identify the least stable mineral.
Olivine is a high-temperature ferromagnesian mineral and weathers very easily at the Earth's surface. \[ \text{Olivine}=\text{least stable} \] So, \[ C \text{ comes last} \]

Step 4: Final sequence.
The decreasing order of weathering stability is: \[ \text{Quartz}>\text{Muscovite}>\text{Hornblende}>\text{Olivine} \] Using the given letters: \[ B>A>D>C \] \[ \therefore \text{Correct Answer is (A)} \]