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What is pegmatite texture?
Pegmatite texture is a coarse-grained igneous rock texture characterized by exceptionally large crystals. These crystals can be several centimeters to several meters in size. The slow cooling of molten rock in pegmatite formations allows for the growth of such large crystals.
Vein of extremely large grained minerals?
This is likely a pegmatite, which is a type of igneous rock known for its exceptionally large crystals. Pegmatites can contain minerals such as quartz, feldspar, and mica that have grown to substantial sizes due to the slow cooling and high concentrations of elements in the magma from which they formed. These minerals are often sought after by collectors for their impressive size and clarity.
Why do igneous rocks that cool quickly have smooth and shiny textures?
Igneous rocks that cool quickly do not have time to form large crystals. This results in a fine-grained texture that appears smooth and may reflect light in a shiny manner. Examples of these rocks include basalt and obsidian.
Which igneous rocks would be formed by the fastest cooling of lava?
Glassy textured extrusive igneous rock, such as obsidian.
What does igneous rock looks like?
Igneous rocks can have a variety of appearances. They can be glassy (obsidian), fine-grained (basalt), or coarse-grained (granite). Igneous rocks often exhibit interlocking crystals in various colors, depending on the mineral composition.
What is pegmatite texture?
Pegmatite texture is a coarse-grained igneous rock texture characterized by exceptionally large crystals. These crystals can be several centimeters to several meters in size. The slow cooling of molten rock in pegmatite formations allows for the growth of such large crystals.
Is obsidian course grained?
fine grained
What igneous rock has no visible crystals?
Granite is a coarse grained igneous rock without Pyroxene.
Is obsidian course-grained or fine-grain?
fine grained
Does obsidian a glassy rock have a large grain size or a small grain size?
Actually, obsidian doesn't have grains at all. Technically obsidian is a glass, which means it has no internal structure. When geologists refer the the grain size of a rock, they mean how big the crystals that make it up are. Since obsidian has no crystals, it therefore has no grain size.
What is the difference between fine-grained and coarse-grained?
Fine grained has larger crystals and coarse grained has smaller crystals
What is the difference between coarse-grained and fine-grained?
Fine grained has larger crystals and coarse grained has smaller crystals
What is a pegmatite texture?
A pegmatite is an intrusive igneous rock comprised of coarse, interlocking mineral grains usually above three centimeters in diameter. Although very many pegmatites are granitic in composition, several hundred mineral species have been found in the most famous pegmatites worldwide, including many rare and valuable minerals. A few discovered pegmatite crystals have grown to several meters across.
What is a glassy grained extrusive rock?
Obsidian.
What is a black volcanic rock with small crystals?
The black volcanic rock with small crystals is most likely basalt. Basalt is fine-grained and is commonly found in volcanic regions as a result of solidified lava flows. The small crystals are often composed of minerals such as plagioclase and pyroxene.
Does obsidian have a large grain size or a small grain?
Obsidian has a small grain size due to its volcanic origin, which means that it cools quickly and does not have time to form large crystals. It is typically fine-grained and exhibits a glassy appearance.
Vein of extremely large grained minerals?
This is likely a pegmatite, which is a type of igneous rock known for its exceptionally large crystals. Pegmatites can contain minerals such as quartz, feldspar, and mica that have grown to substantial sizes due to the slow cooling and high concentrations of elements in the magma from which they formed. These minerals are often sought after by collectors for their impressive size and clarity.
