\Ba*salt"\, n. [N. basaltes (an African word), a dark and
hard species of marble found in Ethiopia: cf. F. basalte.]
1. (Geol.) A rock of igneous origin, consisting of augite and
   triclinic feldspar, with grains of magnetic or titanic
   iron, and also bottle-green particles of olivine
   frequently disseminated.
Note: It is usually of a greenish black color, or of some
      dull brown shade, or black. It constitutes immense beds
      in some regions, and also occurs in veins or dikes
      cutting through other rocks. It has often a prismatic
      structure as at the Giant's Causeway, in Ireland, where
      the columns are as regular as if the work of art. It is
      a very tough and heavy rock, and is one of the best
      materials for macadamizing roads.
2. An imitation, in pottery, of natural basalt; a kind of
   black porcelain.