* Intrusive rocks cool slowly. This slow cooling allows crystals to grow larger, leading to a coarser texture with visible crystals. This is why intrusive rocks like granite are often described as coarse-grained.
* Intrusive rocks can be fine-grained. If the magma cools quickly, even within the Earth, the crystals won't have time to grow large. This results in a fine-grained texture, which can feel smooth.
* Intrusive rocks can have a variety of textures. The texture of an intrusive rock depends on how quickly it cools and the minerals present. Some intrusive rocks can even have a glassy texture if they cool very quickly.
In summary: While intrusive rocks are known for their coarse texture, they can also have fine-grained and even glassy textures depending on their cooling history. So, "rough and coarse" is not a universal characteristic of intrusive rocks.
