Which Rocks term is correctly associated with rock classification: “a fine-grained sedimentary rock”, and also with “formed from compacted mud and clay”?

Correct Answer: Option A — Shale. Shale is correct because it is a fine-grained sedimentary rock. Shale is also associated with formed from compacted mud and clay. A further identifying fact is that Shale is splits into thin layers called fissility. Another useful fact is that Shale is associated with can metamorphose into slate. Why the other options are incorrect: Option B — Marble: It is a metamorphic rock and is associated with formed mainly by metamorphism of limestone; those are the identifying facts of Marble. Option C — Slate: It is a low-grade metamorphic rock and is associated with formed mainly from shale under pressure and heat; those are the identifying facts of Slate. Option D — Quartzite: It is a hard metamorphic rock and is associated with formed from sandstone rich in quartz; those are the identifying facts of Quartzite. Exam Takeaway: Link Shale with “a fine-grained sedimentary rock” and “formed from compacted mud and clay” for quick revision.