Silicate Minerals

Silicate minerals are among the most important and abundant minerals on Earth, constituting about 90% of the planet’s crust. These minerals are divided into two groups: dark silicates (containing iron and magnesium) and light silicates (lacking iron and magnesium). Olivine, pyroxene, amphibole, biotite, tourmaline, talc, serpentine, and asbestos are examples of dark silicates, whereas quartz, the feldspar group, muscovite, and kaolinite belong to the second group. The fundamental structural unit of these minerals is the SiO₄⁴⁻ tetrahedron.

Structural Classification

Based on the arrangement and connection of tetrahedra, silicate minerals are classified into the following groups:

1. Nesosilicates

Tetrahedra that occur as isolated units.
Examples: Olivine, Zircon

2. Sorosilicates

Two linked tetrahedra.
Example: Epidote

3. Cyclosilicates

Ring structures composed of tetrahedra.
Examples: Tourmaline, Beryl

4. Inosilicates

Chain structures (single or double chains).

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  Single-chain: Pyroxenes

  
  


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  Double-chain: Amphiboles

  
  

5. Phyllosilicates

Sheet-like (layered) structures.
Examples: Micas, Talc, Chlorites

6. Tectosilicates

Three-dimensional frameworks of interconnected tetrahedra.
Examples: Quartz, Feldspars, Zeolites