Table of Contents
What is the composition of metamorphic rocks?
Pelitic metamorphic rocks contain alumina-rich minerals such as the micas, garnet, andalusite, kyanite, silliminate, or staurolite. Pelitic metamorphic rocks formed during regional metamorphism include many varieties of slate, phyllite, schist, and gneiss.
What is texture in metamorphic rocks?
Metamorphic texture is the description of the shape and orientation of mineral grains in a metamorphic rock. Metamorphic rock textures are foliated, non-foliated, or lineated are described below.
What are 3 common metamorphic rocks?
Common metamorphic rocks include phyllite, schist, gneiss, quartzite and marble.
How are metamorphic rocks classified by texture?
Classification of Metamorphic Rocks. As with igneous and sedimentary rocks, metamorphic rocks are classified on the basis of texture (grain size, shape, orientation) and mineral composition. For example, greenschist (shale parent) and greenstone (mafic igneous parent).
What are the five basic textures of metamorphic rocks?
They are stable at high temperatures and pressures and may remain chemically unchanged during the metamorphic process. However, all minerals are stable only within certain limits, and the presence of some minerals in metamorphic rocks indicates the approximate temperatures and pressures at which they were formed.
What is the texture of this rock?
The texture of a rock is the size, shape, and arrangement of the grains (for sedimentary rocks) or crystals (for igneous and metamorphic rocks). Also of importance are the rock’s extent of homogeneity (i.e., uniformity of composition throughout) and the degree of isotropy.
What are the common textures?
There are six main types of textures; phaneritic, aphanitic, porphyritic, glassy, pyroclastic and pegmatitic.
What kind of textures are found in metamorphic rock?
Metamorphic Rock Texture The new metamorphic textures are of two types, granular (also non-foliated) where the grains are equidimensional, and foliated where the minerals are layered .
How does the composition of a parent rock affect metamorphism?
Chemical reactions of many sorts occur during metamorphism. Different parent-rock compositions produce different kinds of metamorphic rocks. The composition of the parent rock determines the metamorphic minerals and rocks that may form.
What kind of minerals grow during burial metamorphism?
When rocks undergo burial metamorphism, they encounter a uniform stress of lithostatic pressure, and do not develop foliation. The main type of mineral that usually grows during this metamorphism is zeolite, which is a group of low-density silicate minerals.
How are igneous rocks and metamorphic rocks formed?
These are the rocks that form by the effects of heat, pressure, and shear upon igneous and sedimentary rocks. Some form during mountain-building by forces of others from the heat of igneous intrusions in regional metamorphism others from the heat of igneous intrusions in contact metamorphism.