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Are igneous rocks smooth?
They may be smooth and others may be rough. Smoothness/roughness is not a defining characteristic for igneous rocks.
How do you classify igneous rocks from other types of 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.
Do phaneritic igneous rocks contain viewable crystals?
By definition, yes. In contrast, aphanitic rocks do not have visible crystals.
Is it true that most lava crystallizes to form igneous rocks with phaneritic textures?
No, not all lava crystallizes to form igneous rocks with phaneritic textures. Phaneritic textures are characterized by large, visible crystals, which form when magma cools slowly beneath the Earth's surface. Lava that cools quickly on the Earth's surface forms igneous rocks with aphanitic textures, characterized by fine-grained or glassy structures.
What igneous rock has crystals that are not visible?
Extrusive igneous rock consists of mineral crystals that are not observable with the naked eye. Obsidian is an extrusive igneous rock (volcanic glass) where there technically are no mineral crystals.
What is the term given to igneous rocks with crystals too small to see without a hand lens?
These are extrusive igneous rocks with an aphanitic texture.
What igneous rock is aphanitic texture?
These are igneous rocks that are too fine textured to an extent that there mineral grains or crystalline texture cannot be seen or distinguished with the necked or unaided eyes. They appear or occur as a whole single massive crystalline extrusive body of Igneous origin. Example is Obsidian.
Which igneous rock cools the fastest glassy aphanitc pegmatic and porphyritic?
Glassy igneous rocks cool the fastest. The most likely had more nucleation. Pegmatic cooled the slowest, which is why its crystals are larger than 1 cm. Phaneritic is the next slowest in cooling. Porphyritic has slow then rapid cooling, while aphanitic igneous rocks also have rapid cooling.
Are igneous rocks smooth?
They may be smooth and others may be rough. Smoothness/roughness is not a defining characteristic for igneous rocks.
Igneous rocks are classified based upon their mineral composition and?
And their texture, which can be aphanitic, phaneritic, glassy, or porphyritic. mineral composition and crystal texture
If the lava cools quickly the crystal are what?
If lava cools quickly, the minerals don't have as much time to form crystals, so the crystals do not become very large. Igneous rocks that cooled quickly and have small crystals are described as "aphanitic" igneous rocks.
How do you classify igneous rocks from other types of 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.
Which igneous rocks fine grained due to fast cooling?
When igneous rocks form by cooling quickly, their microstructure includes fine grains. It is the aphanitic igneous rock that includes andesite, basalt, and rhyolite. Wikipedia has more information, and a link is provided below. If you wish to wade on into the depths of rock microstructures, you can link on from there.
Some WHAT igneous rocks have individual mineral crystals that are too small to be seen without magnification?
Aphanitic igneous rocks have individual mineral crystals that are too small to be seen without magnification. These rocks cool rapidly, resulting in the formation of tiny crystals. Examples include basalt and rhyolite.
Do phaneritic igneous rocks contain viewable crystals?
By definition, yes. In contrast, aphanitic rocks do not have visible crystals.
Is it true that most lava crystallizes to form igneous rocks with phaneritic textures?
No, not all lava crystallizes to form igneous rocks with phaneritic textures. Phaneritic textures are characterized by large, visible crystals, which form when magma cools slowly beneath the Earth's surface. Lava that cools quickly on the Earth's surface forms igneous rocks with aphanitic textures, characterized by fine-grained or glassy structures.
What igneous rock has crystals that are not visible?
Extrusive igneous rock consists of mineral crystals that are not observable with the naked eye. Obsidian is an extrusive igneous rock (volcanic glass) where there technically are no mineral crystals.
