A quarry is where rock fragments of particular size have been excavated.
Gravel [ ˈɡrævəl ] is the study of rock fragments that have a general particle size range and include size classes from granule - to boulder-sized fragments . Greywacke or Graywacke ( German grauwacke , signifying a grey , earthy rock ) is a variety of sandstone generally characterized by its hardness , dark color , and poorly sorted angular grains of quartz , feldspar , and small rock fragments or lithic fragments set in a compact , clay-fine matrix . A quarry is a place from which dimension stone , rock , construction aggregate , riprap , sand , gravel , or slate has been excavated from the ground .