The texture is really glassy, like obsidian.
super fine grained rock
it is extrusive
The texture would be glass-like.
Rapid cooling of lava in which tiny crystals form results in a glassy texture.
The resultant rock would have a porphyritic texture; large crystals (usually feldspars) scattered among small crystal grains.
When igneous rocks cool quickly, they have small crystals and have a texture that may be described as aphanitic. When igneous rocks cool slowly, they have much larger crystals and have a texture that may be described as phaneritic or pegmatitic.
Slow cooling of molten rock leads to rocks with an phaneritic texture; one with larger, visible mineral crystals.
The texture would be glass-like.
They are said to have a glassy or vitreous texture.
super fine grained rock
Rapid cooling of lava in which tiny crystals form results in a glassy texture.
The resultant rock would have a porphyritic texture; large crystals (usually feldspars) scattered among small crystal grains.
They form from the extremely rapid cooling of lava or magma. The quick cooling does not allow time for the crystallization of minerals, resulting in the formation of a natural glass.
Phaneritic.
Fine-grained
When igneous rocks cool quickly, they have small crystals and have a texture that may be described as aphanitic. When igneous rocks cool slowly, they have much larger crystals and have a texture that may be described as phaneritic or pegmatitic.
Slow cooling of molten rock leads to rocks with an phaneritic texture; one with larger, visible mineral crystals.
Yes, extrusive rocks are rocks that cool rapidly on the surface. Because of the rapid cooling the phenocrysts have little time to grow. Thus resulting in a type of aphanitic texture. Large phenocrysts can be referred to as porphyritic and it is has crystals that are over a certain diameter.
The texture depends on the size and shape of the crystals you see in it. The larger the crystals, the slower the rate of cooling. This suggests that it is an intrusive rock. Smaller crystals suggest more rapid cooling indicating that it is an extrusive rock. INTRUSIVE- cooled inside the earth and had more time to create crystals EXTRUSIVE- cooled on the surface of the earth and created small crystals