Mica is a mineral that is commonly found in certain types of rocks. In this question, the correct answer is option 2, Schist-Gneiss. Both schist and gneiss are metamorphic rocks that can contain mica. Metamorphic rocks are formed when existing rocks are subjected to high temperatures and pressures, causing them to change in composition and structure. Mica is often found in these rocks because it forms in layers during the metamorphic process. Option 1, Slate-Sandstone, is not correct because neither slate nor sandstone typically contain mica. Option 3, Limestone-Sandstone, is also incorrect as both limestone and sandstone do not usually contain mica. Option 4, Shale-Limestone, is not correct as shale rarely contains mica, and while limestone may occasionally contain small amounts of mica, it is not as common as in schist and gneiss.