Admin What is the parallel alignment of minerals called?
Foliation is produced in a rock by the parallel alignment of platy minerals (e.g., muscovite, biotite, chlorite), needle-like minerals (e.g., hornblende), or tabular minerals (e.g., feldspars). This parallel alignment causes the rock to split easily into thin layers or sheets. Banding, by itself, defines a foliation.
Why are metamorphic rocks formed in a parallel pattern?
Foliated Metamorphic Rocks: Foliation forms when pressure squeezes the flat or elongate minerals within a rock so they become aligned. These rocks develop a platy or sheet-like structure that reflects the direction that pressure was applied.
What type of stress that occurs during metamorphism results in aligned and elongated minerals?
When a rock is squeezed under directed pressure during metamorphism it is likely to be deformed, and this can result in a textural change such that the minerals are elongated in the direction perpendicular to the main stress (Figure 7.5). This contributes to the formation of foliation.
Which type of pressure will result in the alignment of metamorphic minerals?
between 100 and 300 MPa
The metamorphic process usually occurs at pressures between 100 and 300 MPa, the depth at which these pressures occur depending on which type of rock is applying pressure.
What is Phaneritic and Aphanitic?
• Categorized under Geography | Difference between aphanitic and phaneritic. Aphanite and phanerite are two different forms of rocks.
When metamorphic rocks have a preferred mineral orientation of aligned Inequant crystals they are said to have a texture?
A foliated metamorphic rock has foliation either because it contains inequant mineral crystals that are aligned parallel to one another, defining preferred mineral orientation, and/or because the rock has alternating dark-coloured and light-coloured layers.
What texture is formed in the alignment of mineral crystals with a preferred orientation in a metamorphic?
foliation
Foliated – These have a planar foliation caused by the preferred orientation (alignment) of minerals and formed under differential stress.
What is a Phenocrysts in geology?
« Back to Glossary Index. A large crystal within an igneous rock. These can be seen within phaneritic and porphyritic rocks.