Here's a breakdown of granite's grain pattern:
* Equigranular: The crystals are roughly the same size. This is the most common type of granite grain pattern.
* Inequigranular: The crystals are of varying sizes. This can create a more interesting and varied look.
* Porphyritic: The granite contains larger crystals (phenocrysts) embedded within a matrix of smaller crystals.
* Pegmatitic: The granite contains exceptionally large crystals, often exceeding several inches in size.
What determines the grain pattern?
The grain pattern of granite is primarily determined by the cooling rate of the magma from which it forms:
* Slow cooling: Allows for larger crystals to grow, resulting in a coarser grain.
* Fast cooling: Leads to smaller crystals, resulting in a finer grain.
Granite's grain pattern, along with its color and mineral composition, contributes to its unique beauty and makes it a popular choice for building materials and decorative objects.
