Final answer:
The medium-grain-sized metamorphic rock that is composed mostly of the same mineral as limestone is marble, which forms through the recrystallization of the carbonate minerals under heat and pressure.
Step-by-step explanation:
The medium-grain-sized metamorphic rock that is composed mostly of the same mineral as the sedimentary rock limestone is marble. Marble forms from the metamorphism of limestone or dolomite, which are made primarily of the mineral calcite. The process involves recrystallization under heat and pressure, where the original carbonate mineral grains grow in size and the rock becomes more dense and crystalline.
Limestone, when subjected to the conditions mentioned, can change its form to become marble. This transformation is a result of the heat and pressure, which causes the texture and chemical composition of the original limestone to alter. Unlike marble, gneiss, quartzite, and schist have different mineral compositions and are formed from different types of parent rocks. Gneiss is formed from high-grade metamorphism of schists or granites, quartzite comes from the metamorphism of quartzose sandstones or siltstones, and schist forms at a lower grade than gneiss.