Igneous Textures

1. Types of Textures 

   1. Primary: occur during crystallization and results from the interactions of the melt and crystals 

   2. Secondary: alterations that take place AFTER the rock is completely solid 

2. Formation of growth of crystals 

   1. Initial nucleation → subsequent crystal growth → diffusion of chemical species 

   2. Nucleation: clustering of critical size of compatible ions → supersaturation 

   3. Undercooling: cooling of melt way below the true crystallization temperature of the mineral 

   4. Crystals with simpler structures → complex structures 

   5. Crystal growth: addition of ions onto already existing crystals or crystal nuclei

Diffusion of chemical species: for mineral growth to continue, new material must diffuse through the melt, the depleted zone, and reach the crystal’s surface.

• Nucleation: the initial process where small clusters of atoms or molecules form, serving as a template for further crystal growth.

• Cooling rate: The rate at which magma cools significantly affects the size and arrangement of crystals, leading to various textures such as fine-grained, coarse-grained, or glassy.