fine grained
fine grained
Obsidian.
vitreous or glassy (obsidian)
Yes extrusive rocks are fine grained because they cool down at a faster rate.
This description likely fits obsidian, a natural glass formed from rapidly cooling lava. Obsidian is characterized by its fine-grained texture and shiny, smooth surface. It is commonly black, but can also be found in other colors like brown, red, or green.
Coarse
Gneiss is course grained but it has a fabric.
Granite is a coarse grained igneous rock without Pyroxene.
G
Obsidian
Three types of igneous rocks are basalt, granite, and obsidian. Basalt is a dark-colored fine-grained rock, granite is a light-colored coarse-grained rock, and obsidian is a natural glass formed from rapidly cooled lava.
shale