magma or lava controls most texture in igneous rock
Igneous rocks are identified by first looking at the color index. Felsic igneous rocks contain mostly potassium feldspar. Intermediate igneous rocks contain mostly plagioclase feldspar. Mafic igneous rocks contain pyroxene, olivine, and plagioclase feldspar. Ultra mafic igneous rocks contain mostly olivine. Then igneous rocks are identified based on texture. For example, the texture of igneous rocks can be aphanitic, pegmatitic, phaneritic, glassy, vesicular, etc.
Rocks with an aphanitic texture have fine-grained crystals that are too small to be seen by the naked eye. Common igneous rocks with this texture include basalt, andesite, and rhyolite. These rocks cool quickly at the Earth's surface, preventing larger crystals from forming.
Granite, diorite, and gabbro are examples of igneous rocks that do not have a glassy texture. These rocks are formed from slowly cooled magma underground, allowing time for crystals to grow, giving them a coarse-grained appearance.
Igneous rocks are generally classified first on the basis of their formation (and therefore their texture) as intrusive or extrusive. Intrusive rocks are solidified from magma under the surface resulting in a visible crystalline texture, and extrusive igneous rocks are solidified from lava at or near the surface, resulting in a small or nearly invisible crystalline texture. Igneous rock can additionally be classified by general chemistry composition as felsic, intermediate, mafic, and ultramafic. Felsic rocks are higher in silica and aluminum. Mafic rocks are higher in magnesium and iron.
The texture of igneous rocks with large crystals that form from slow cooling is called phaneritic. This texture indicates that the minerals had enough time to grow large enough to be visible to the naked eye. Examples of rocks with phaneritic texture include granite and diorite.
Phaneritic is the texture of igneous rocks. These types of rocks crystallized slowly.
Crystalline texture.
Obsidian
yes
Igneous rocks are identified by first looking at the color index. Felsic igneous rocks contain mostly potassium feldspar. Intermediate igneous rocks contain mostly plagioclase feldspar. Mafic igneous rocks contain pyroxene, olivine, and plagioclase feldspar. Ultra mafic igneous rocks contain mostly olivine. Then igneous rocks are identified based on texture. For example, the texture of igneous rocks can be aphanitic, pegmatitic, phaneritic, glassy, vesicular, etc.
The relationship between an igneous rock's texture and where it was formed is that the texture depends on whether or not the rock is an extrusive rock or an intrusive rock. Those two different types of classifications for rocks tell you what the texture will be. For example, Intrusive rocks have a coarse-grained texture like granite and extrusive rocks have a fine-grained texture like basalt.
Course grained texture.
Correct, porphyritic texture is typically associated with igneous rocks and is not a common feature of sedimentary rocks. It is characterized by larger crystals, known as phenocrysts, surrounded by a fine-grained or glassy matrix. Sedimentary rocks are formed through the accumulation and lithification of sediments, which do not typically undergo the same crystallization processes as igneous rocks.
Rocks with an aphanitic texture have fine-grained crystals that are too small to be seen by the naked eye. Common igneous rocks with this texture include basalt, andesite, and rhyolite. These rocks cool quickly at the Earth's surface, preventing larger crystals from forming.
These are extrusive igneous rocks with an aphanitic texture.
Granite, diorite, and gabbro are examples of igneous rocks that do not have a glassy texture. These rocks are formed from slowly cooled magma underground, allowing time for crystals to grow, giving them a coarse-grained appearance.
Look at them. There shape, size, color and feel! Dont worry you will figure it out....