Question

Which one or more of the following minerals shows O:Si ratio of 4:1 in its silicate structure?

• A. Olivine
• B. Quartz
• C. Diopside
• D. Albite

Hint:

- Nesosilicates → Isolated tetrahedra, O:Si = 4:1 (e.g., Olivine, Garnet).
- Inosilicates → Chains, O:Si = 3:1 or 2.75:1.
- Tectosilicates → Framework, O:Si = 2:1.

Answer 1

The Correct Option is A

Step 1: Recall the silicate structural classification.
Silicate minerals are classified based on the arrangement of \(\text{SiO}_4\) tetrahedra and the resulting O:Si ratio: - Nesosilicates (isolated tetrahedra): O:Si = 4:1
- Inosilicates (single chain): O:Si = 3:1
- Inosilicates (double chain): O:Si = 2.75:1
- Phyllosilicates (sheets): O:Si = 2.5:1
- Tectosilicates (framework, e.g., quartz, feldspars): O:Si = 2:1 Step 2: Check each mineral.
- Olivine (Mg,Fe)\(_2\)SiO\(_4\): A nesosilicate, with isolated \(\text{SiO}_4\) tetrahedra. → O:Si = 4:1
- Quartz (SiO\(_2\)): A tectosilicate with a 3D framework. → O:Si = 2:1
- Diopside (CaMgSi\(_2\)O\(_6\)): A pyroxene, single chain inosilicate. → O:Si = 3:1
- Albite (NaAlSi\(_3\)O\(_8\)): A feldspar, tectosilicate. → O:Si = 2:1 Step 3: Conclusion.
Only Olivine has the O:Si ratio of 4:1. Final Answer: \[ \boxed{\text{Olivine}} \]