Intrusive (plutonic) igneous rock. Explanation:
- When magma cools slowly below the Earth’s surface, crystals have time to grow large, producing intrusive or plutonic igneous rocks such as granite, diorite, and diabase. This slow cooling yields coarse-grained textures that are visible to the naked eye.
- This is in contrast to extrusive (volcanic) rocks, which form from rapid cooling at or near the surface and typically have fine-grained textures or glass; examples include rhyolite, andesite, basalt, and obsidian.
If you’d like, I can summarize how cooling rate affects mineral textures in igneous rocks, or list common intrusive rocks with their mineral compositions.
