Question

Non-ferromanesian group of minerals are ----

• A. Inosilicates
• B. Phyllosilicates
• C. Tectosilicates
• D. Cyclosilicates

Hint:

Quartz and Feldspars make up over \( 60\% \) of the Earth's crust and are the most common Tectosilicates.
Because they contain no iron or magnesium, they are the primary non-ferromagnesian minerals.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Silicate minerals are classified into ferromagnesian (containing significant amounts of iron and magnesium, usually dark-colored and dense) and non-ferromagnesian (lacking iron and magnesium, light-colored and less dense) groups.

Step 2: Detailed Explanation:
Let us analyze the structural groups of silicates:
- Ferromagnesian minerals: Include minerals like olivine (neosilicate), pyroxene (inosilicate), and amphibole (double-chain inosilicate).
These contain high concentrations of divalent cations of iron (\(\text{Fe}^{2+}\)) and magnesium (\(\text{Mg}^{2+}\)).
- Non-ferromagnesian minerals: These minerals are rich in silica, aluminum, sodium, potassium, and calcium, and are light-colored.
The primary mineral group representing non-ferromagnesian minerals is Tectosilicates (framework silicates).
Tectosilicates feature a continuous three-dimensional network of silicon-oxygen tetrahedra where all four oxygen atoms are shared, chemically formulated as \(\text{SiO}_2\).
Key examples of tectosilicates include Quartz (\(\text{SiO}_2\)), Orthoclase feldspar (\(\text{KAlSi}_3\text{O}_8\)), and Plagioclase feldspar (\(\text{NaAlSi}_3\text{O}_8 - \text{CaAl}_2\text{Si}_2\text{O}_8\)).
These minerals do not contain iron or magnesium in their crystal structures, making them the classic non-ferromagnesian minerals.

Step 3: Final Answer:
The non-ferromagnesian group of minerals are Tectosilicates.