Which Rocks term is correctly associated with identifying feature: “dark-coloured and fine-grained”, and also with “common in oceanic crust and lava plateaus”?

Correct Answer: Option C — Basalt. Basalt is correct because it is dark-coloured and fine-grained. Basalt is also associated with common in oceanic crust and lava plateaus. A further identifying fact is that Basalt is dark-coloured and fine-grained. Another useful fact is that Basalt is associated with common in oceanic crust and lava plateaus. Why the other options are incorrect: Option A — Pumice: It is so porous that some pieces can float on water and is associated with used as an abrasive and lightweight aggregate; those are the identifying facts of Pumice. Option B — Obsidian: It is glassy texture with conchoidal fracture and is associated with historically used for sharp cutting tools; those are the identifying facts of Obsidian. Option D — Sandstone: It is often shows bedding layers and is associated with commonly used as a building stone; those are the identifying facts of Sandstone. Exam Takeaway: Link Basalt with “dark-coloured and fine-grained” and “common in oceanic crust and lava plateaus” for quick revision.