SOLVED

42) At high pressures and elevated temperatures of regional metamorphism, silicate rocks are more resistant to flowage and deformation than at low temperatures and pressures. 43) Foliated metamorphic rocks are composed largely of equidimensional grains of minerals such as quartz and calcite. 44) Rock cleavage or slaty cleavage in slates is largely a consequence of abundant, parallel-aligned, very fine-grained mica flakes in the rock. 45) Muscovite, biotite, and chlorite are common minerals found in phyllites and schists. 46) The distinctive layers or bands of different minerals in gneisses may be complexly folded. 47) Metaconglomerates are more strongly foliated than migmatite. 48) High-grade, regional metamorphism produces significant and recognizable changes in the textures and mineral compositions of rocks. 49) Talc and graphite are very soft minerals found in some schists. 50) Three major factors involved in metamorphism are elevated temperature, elevated pressure, and the chemical action of hot fluids. 51) During metamorphism, most rock is composed of solid mineral grains, but small amounts of hot fluids or partial melting may facilitate the metamorphic process.