Which one of the following is generally found in sedimentary rocks?

Sedimentary rocks are formed through the lithification, consolidation, and compaction of sediments derived from the weathering and erosion of pre-existing rocks [4]. Shale is a primary example of a mechanically formed (clastic) sedimentary rock, specifically an argillaceous rock composed of clay and silt-sized particles [3][t3]. While silica is a common mineral component (often as quartz) that can act as a cementing agent in sedimentary rocks, it is not a rock type itself [3][t3]. Basalt is explicitly classified as an extrusive igneous rock rich in magnesium and iron [t4][t7]. Magnesium is a chemical element found in various minerals but is not a rock. Therefore, among the given options, shale is the definitive rock type generally found in sedimentary formations [4][t1].

Sources

1. [4] https://www.usgs.gov/faqs/what-are-sedimentary-rocks
2. [1] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 13: Types of Rocks & Rock Cycle > Some Examples of Metamorphosis > p. 174
3. [3] Certificate Physical and Human Geography , GC Leong (Oxford University press 3rd ed.) > Chapter 2: The Earth's Crust > SEDIMENTARY ROCKS > p. 18