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Basalt is a common extrusive igneous (volcanic) rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. By definition, basalt must be an aphanitic igneous rock with less than 20% quartz and less than 10% feldspathoid by volume, and where at least 65% of the feldspar is in the form of plagioclase. (In comparison, granite has more than 20% quartz by volume.) Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic (iron-rich) minerals into rust. It almost always has a fine-grained mineral texture due to the molten rock cooling too quickly for large mineral crystals to grow, although it can sometimes be porphyritic, containing the larger crystals formed prior to the extrusion that brought the lava to the surface, embedded in a finer-grained matrix. Basalt with avesicular or frothy texture is called scoria, and forms when dissolved gases are forced out of solution and form vesicles as the lava decompresses as it reaches the surface.
Wiki User
∙ 11y ago
Wiki User
∙ 12y agobasalt magmas have formed by decompression melting of the mantle
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What kind of rocks are ajanta caves made of?
hard basalt rock of deccan trap
Basalt and granite belong to which type of rocks?
Igneous rocks
How do gabbro and basalt rocks form?
The magma cools and forms both rocks
What type of hawaiian rocks have low permeability?
Basalt
What are types of volcanic rock?
Volcanic rocks are extrusive igneous rocks.
What are most rocks in the lunar Maria made of?
Basalt
What is mid ocean ridge molten rocks made out of?
Basalt. Basalt - Wikipedia, the free encyclopedia
What rock is a obsidian and basalt?
Obsidian and Basalt are both Igneous rocks. They are made from hardened lava from volcanoes.
What layer of the Earth is made up of the rocks basalt and granite?
The crust.
What is made of baUxite?
silicate rocks, such as granite, gneiss, basalt, and shale.
What kind of rocks are ajanta caves made of?
hard basalt rock of deccan trap
The layer of Earth made up largely of the rocks basalt and granite is the?
The crust.
What type of igneous rocks are kerbstones made out of?
Commonly basalt, a volcanic; or granite.
Are basaltic igneous rocks lower in density than granitic rocks?
Granite is very much less dense than basalt. This is why the continental crust (mostly composed of granite) floats on Oceanic crust (made mostly of basalt). Granite is 70 % silicon. Where basalt is mainly pyroxene.
What types of rocks are basalt and granite?
They are all igneous rocks.
Basalt and granite belong to which type of rocks?
Igneous rocks
What does granite and basalt have in common?
Basalt and Granite are igneous rocks which are very hard.
