Silicic Rocks

Silicic Rocks

1. Light in colour

2. Light in density

3. High in silicon and oxygen

4. High in Feldspar

   • Plagioclase
     • Up to 25%
   • Orthoclase
     • Up to 40%

5. High Quartz content

   • 20% at most

6. High in Mica

   • Up to 15%

7. Low in Mafic minerals

   • Can sometimes have 0%

8. Intrusive

   • Coarse grained (crystals can be seen with naked eye)
     • Granite
     • Diorite
     • Syenite
   • Medium grained (requires maginfying glass)
     • Micro - granite
     • Micro - syneite
     • Micro - diorite

9. Extrusive

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