#rock.natural_object__stone  a lump of hard consolidated mineral matter; "he threw a rock at me"
  supertype:  natural_object__naturalobject  an object occurring naturally; not made by man
  subtype:  achondrite  a stony meteor lacking chondrules
  subtype:  bedrock  solid unweathered rock lying beneath surface deposits of soil
  subtype:  boulder__bowlder  a large smooth mass of rock detached from its place of origin
     subtype:  glacial_boulder__glacialboulder  a boulder that has been carried by a glacier to a place far distant from its place of origin
     subtype:  river_boulder__riverboulder  a boulder that has been carried by a river to a place remote from its place of origin
     subtype:  shore_boulder__shoreboulder  a boulder found on a shore remote from its place of origin
     instance:  Plymouth_Rock.boulder__plymouthrock
  subtype:  calculus__stone__concretion  a hard lump produced by the concretion of mineral salts; found in hollow organs or ducts of the body
     subtype:  bladder_stone__bladderstone__cystolith  a calculus formed in the bladder
     subtype:  enterolith  a calculus occurring in the intestines
     subtype:  gallstone__bilestone  a calculus formed in the gall bladder or its ducts
     subtype:  kidney_stone__urinary_calculus__nephrolith__renal_calculus  a calculus formed in the kidney
     subtype:  ptyalith  calculus in a salivary gland
     subtype:  sialolith__salivary_calculus  a stone formed in the salivary gland
     subtype:  urolith  a urinary stone
  subtype:  chondrite  a rock of meteoric origin containing chondrules
  subtype:  crystal.rock  a rock formed by the solidification of a substance; has regularly repeating internal structure; external plane faces
     subtype:  crystallite  any of numerous minute rudimentary crystalline bodies of unknown composition found in glassy igneous rock
  subtype:  rock_outcrop__outcrop__outcropping  the part of a rock formation that appears above the surface of the surrounding land
     subtype:  belay  something to which a mountain climber's rope can be secured
     subtype:  outthrust  an outcropping of rock that extends outward
  subtype:  pebble  a small smooth rounded rock
  subtype:  petrifaction  a rock created by petrifaction; an organic object infiltrated with mineral matter and preserved in its original form
  subtype:  sill.rock  (geology) a flat (usually horizontal) mass of igneous rock between two layers of older sedimentary rock
  subtype:  stepping_stone.rock__steppingstone  a stone in a marsh or shallow water that can be stepped on in crossing
  subtype:  tor.rock  a prominent rock or pile of rocks on a hill
  subtype:  wall_rock  a rock immediately adjacent to a vein or fault

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