 The continental crust consists of lower density material such as the igneous rocks granite and andesite . Less common is basalt , a denser volcanic rock that is the primary constituent of the ocean floors . Sedimentary rock is formed from the accumulation of sediment that becomes buried and compacted together . Nearly 75 % of the continental surfaces are covered by sedimentary rocks , although they form about 5 % of the crust . The third form of rock material found on Earth is metamorphic rock , which is created from the transformation of pre @-@ existing rock types through high pressures , high temperatures , or both . The most abundant silicate minerals on Earth 's surface include quartz , feldspars , amphibole , mica , pyroxene and olivine . Common carbonate minerals include calcite ( found in limestone ) and dolomite . 
