The main minerals constituents of the continental mass are and .

Question

Question

This question was previously asked in

SSC MTS (2022) Official Paper (Held On: 08 May 2023 Shift 1)

Answer 1

The correct answer is 'silica, alumina'

Key Points

Silica (SiO₂) and Alumina (Al₂O₃):
- The continental crust is primarily composed of silicate minerals, which are rich in silica and alumina.
- These compounds form the bulk of minerals such as feldspar and quartz, which are the most abundant minerals in the Earth's continental crust.
- Silica (SiO₂) contributes to the crust’s overall light color and low density, characteristic of continental rocks.
- Alumina (Al₂O₃) is a key component of feldspar minerals, which make up about 60% of the Earth's crust.

Additional Information

Oxygen and Carbon:
- Oxygen is indeed a major component of continental crust minerals, making up about 46.6% of the crust by weight.
- Carbon, however, is present in much smaller quantities mainly in carbonate minerals, which are much less abundant in the continental crust compared to silicate minerals.
Silica and Magnesium:
- While silica is a major component of the continental crust, magnesium is more prevalent in the Earth's mantle and oceanic crust.
- Minerals such as olivine and pyroxene, which are rich in magnesium, are found primarily in the mantle and oceanic crust rather than in the continental crust.
Alumina and Magnesium:
- Alumina is a significant component of the continental crust, but pairing it with magnesium overlooks the dominant presence of silica in the continental crust rocks.
- Magnesium, similar to the previous point, is more associated with deeper parts of the Earth's structure such as the mantle and oceanic crust.

Important Points

The composition of the continental crust is crucial for understanding various geological and geochemical processes.
The predominance of silica and alumina gives the continental crust its unique characteristics, such as lower density and different mineralogy compared to the oceanic crust.
This knowledge is fundamental in the study of plate tectonics, mountain-building processes, and the formation of different rock types.